Infectious Pregnancy Complications

Pregnancy and Infants: Medical, Psychological and Social Issues Series

INFECTIOUS PREGNANCY COMPLICATIONS No part of this digital document may be reproduced, stored in a retrieval system or transmitted in any form or by any means. The publisher has taken reasonable care in the preparation of this digital document, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained herein. This digital document is sold with the clear understanding that the publisher is not engaged in rendering legal, medical or any other professional services.

Pregnancy and Infants: Medical, Psychological and Social Issues Series Focus on Milk and Infants Viroj Wiwanitkit 2009. ISBN: 978-1-60741-106-2 Infectious Pregnancy Complications Richard N. Canfield (Editor) 2009. ISBN: 978-1-60471-038-6

Pregnancy and Infants: Medical, Psychological and Social Issues Series

INFECTIOUS PREGNANCY COMPLICATIONS

RICHARD N. CANFIELD EDITOR

Nova Biomedical Books New York

Copyright © 2009 by Nova Science Publishers, Inc. All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical photocopying, recording or otherwise without the written permission of the Publisher. For permission to use material from this book please contact us: Telephone 631-231-7269; Fax 631-231-8175 Web Site: http://www.novapublishers.com NOTICE TO THE READER The Publisher has taken reasonable care in the preparation of this book, but makes no expressed or implied warranty of any kind and assumes no responsibility for any errors or omissions. No liability is assumed for incidental or consequential damages in connection with or arising out of information contained in this book. The Publisher shall not be liable for any special, consequential, or exemplary damages resulting, in whole or in part, from the readers’ use of, or reliance upon, this material. Any parts of this book based on government reports are so indicated and copyright is claimed for those parts to the extent applicable to compilations of such works. Independent verification should be sought for any data, advice or recommendations contained in this book. In addition, no responsibility is assumed by the publisher for any injury and/or damage to persons or property arising from any methods, products, instructions, ideas or otherwise contained in this publication. This publication is designed to provide accurate and authoritative information with regard to the subject matter covered herein. It is sold with the clear understanding that the Publisher is not engaged in rendering legal or any other professional services. If legal or any other expert assistance is required, the services of a competent person should be sought. FROM A DECLARATION OF PARTICIPANTS JOINTLY ADOPTED BY A COMMITTEE OF THE AMERICAN BAR ASSOCIATION AND A COMMITTEE OF PUBLISHERS. Library of Congress Cataloging-in-Publication Data Infectious pregnancy complications / [edited by] Richard N. Canfield. p. ; cm. Includes bibliographical references and index. ISBN 978-1-61668-573-7 (E-Book) 1. Communicable diseases in pregnancy. I. Canfield, Richard N. [DNLM: 1. Pregnancy Complications, Infectious. 2. Communicable Diseases--complications. 3. Genital Diseases, Female--complications. WQ 256 I445 2009] RG578.I545 2009 618.3'6--dc22 2009004979

Published by Nova Science Publishers, Inc.  New York

Contents Preface

vii

Chapter 1

Complications of Infections in Pregnancy Dushyant Maharaj

Chapter 2

Infection Related Recurrent Late Abortions and Preterm Birth: Early Total Cervix Occlusion (ETCO) Versus Cerclage Erich Saling and Monika Dräger

Chapter 3

Virulence of Influenza Virus on Human Fetal Membrane Tissues Noboru Uchide and Hiroo Toyoda

Chapter 4

Serological Response to Rubella, Herpes Simplex 2 and Cytomegalovirus in Pregnant Women with Unexplained Recurrent Abortions Maysaa El Sayed Zaki and Ahmmed Badawy

Chapter 5

Chapter 6

Chapter 7

Chapter 8

Appendicitis during Pregnancy: A Serious Disease and a Diagnostic Problem L. Penninga and E.I. Penninga Mediastinal End Subcutaneous Emphysema as a Complication of Labor Arkadiusz Praski, Włodzimierz Kupis, Marek Florczak and Małgorzata Szpetnar

1

83 111

139

151

159

Program for the Prevention of Infection-Related Premature Births: The Role of the Lactobacilli System and Vaginal pH Erich Saling and Monika Dräger

167

Challenges for the Management of HIV-Infected Pregnant Women in Resource Constrained Settings Stephen Mepham, Ruth Bland and Marie-Louise Newell

199

vi Chapter 9

Chapter 10

Chapter 11

Contents Impact of Materno-Placental Malaria, Anaemia and HIV Infection on Perinatal Outcome in Nigeria C. J. Uneke, I. Sunday-Adeoye, F. E. Iyare, O. G. Asiegbu and D. D. Duhlinska

235

Toxoplasma gondii and Pregnancy: Priorities for Diagnostics of Congenital Infection Alessandra Sensini

289

Screening for Toxoplasma gondii Infection in Pregnancy in an Urban Area of Northern Italy: Management and Problems Massimo De Paschale and Pierangelo Clerici

319

Chapter 12

Rickettsioses in Pregnancy Maria Bitsori and Emmanouil Galanakis

331

Chapter 13

Infectious Diseases of the Urinary Tract during Pregnancy Nándor Ács, Ferenc Bánhidy and Andrew E. Czeizel

345

Chapter 14

Dengue Infection in Pregnancy: Pattern of Hematological Disturbance Viroj Wiwanitkit

Chapter 15

Infectious Diseases of the Respiratory System during Pregnancy Andrew E. Czeizel, Nándor Ács and Ferenc Bánhidy

Chapter 16

Maternal Outcomes in Pregnancy with Smallpox: Epidemiologic Investigations of Case Fatality, Miscarriage and Premature Birth Based on Previous Outbreaks Hiroshi Nishiura

Chapter 17 Index

Chicken Pox Infection in Pregnancy Viroj Wiwanitkit

373 383

407 421 427

Preface Infectious Pregnancy Complications deal with the co-occurrence of pregnancy and an infection. The infection may precede or follow fertilization. This new book presents the latest research in the field. Chapter 1- Epidemiological reports estimate that 7.7 million perinatal deaths occur annually worldwide, including 4.3 million that take place in late pregnancy, while the remaining neonates die in the first weeks of life. Reports attribute the majority of these consequences to infections of the fetus in utero. Infections during pregnancy affect the mother, and often some infections may be transmitted to the fetus in utero, during the intrapartum period or, postnatally, with potentially serious consequences. Many infections have been linked to increased risks of premature delivery and low birth weight, and associated morbidity and mortality of both mother and child. Acute or chronic specific infectious diseases may be contracted during the course of pregnancy, and conception may occur in women already subject to an infection. The coexistence of pregnancy may aggravate the risk to maternal life in cases of the more serious of these diseases. In pregnancy most infections are no more common, nor more serious than in a non-pregnant population of women of similar age. The effects on pregnancy depend on the degree of pyrexia, its duration, and the stage of fetal development when it occurs. Mild exposures during the preimplantation period, and more severe exposures during embryonic and fetal development often result in miscarriage, premature labor, growth restriction, or stillbirth. Hyperthermia may also cause a wide range of fetal structural and functional defects, with the central nervous system (CNS) being most at risk. While there is a greater incidence of neonatal morbidity and mortality with transmitted infections, not all maternal infections lead to transmission to the fetus, nor does transmission to the fetus lead to disease or sequelae. During the puerperium, parturient women are particularly susceptible to serious infections of the genital tract and childbed fever remains one of the most important causes of maternal death. Infections in pregnancy may be viral, bacterial or protozoal, affecting both mother and fetus. Some of the infections cause fevers, while others may not; this chapter will concentrate on infections resulting in maternal pyrexia, and some other infections which may not result in maternal pyrexia, but have important implications for the pregnancy and the fetus.

viii

Richard N. Canfield

Chapter 2 - Recurrent late abortions and early prematurity continue to be two of the main problems of modern obstetrics and perinatal medicine which remain to be fully solved. The patients concerned often suffer increasingly. Ascending genital infection is the main preventable cause for late abortions or early premature births. In recurrent cases, the Early Total Cervix Occlusion (ETCO) is an early preventive measure particularly for women with a history of ≥ 2 late abortions or early premature births (< 32+0 weeks gestation). The operative technique, our own results, and results from a multi-center-enquiry undertaken in Germany are subjects of our present discussion. In both evaluations, the women within this high risk group had a surviving infant in about 70% of cases after a Total Cervix Occlusion (TCO). Differentiated according to „early“ TCO (ETCO) and „late“ TCO, the success rate has been 80% and 40% respectively. Cerclage is still a frequently employed measure in cases with recurrent preterm births, but it has increasingly become the subject of controversy. ETCO is quite different from cerclage. The cerclage only tightens the canal. Whereas ETCO really closes the cervical canal: After the epithelium of the lower cervical canal and of the lower portio has been removed these parts are sutured. This allows the lower cervix to heal up and close totally. This is a complete barrier which thus prevents ascension of organisms The much poorer results inevitably achieved by cerclage are compared with the results of ETCO. In our sample of women treated with ETCO we found that, in 51 previous pregnancies in which cerclage was performed, only 13 infants survived. This is a survival rate of only 26% (as compared to a survival rate of 80% with ETCO). ETCO was developed by us in 1981 in Germany and is widespread in Germany and also used in other German-speaking countries, but it is still rarely performed on an international level. This might partly be due to the fact that randomized studies with ETCO have up to now never been performed. But—considering the excellent results of ETCO—performing such a study now in Germany would raise serious ethical issues. Another possible indication for the future may be in the area of multiple pregnancies: With ETCO, generally performed in multiple pregnancies, Schulze [40] was able to achieve a prematurity rate of only 17% as against a rate of 29% in cases without ETCO. In the group of infants at very high risk (< 28 weeks gestation), the rate with ETCO was 1% as opposed to 4% without. More information on: http://www.saling-institut.de/eng/04infoph/04tmv.html. Chapter 3 - An increase of the risk of premature delivery, abortion and stillbirth has been observed during the past pandemics of influenza. The occurrence of intrauterine influenza virus infection during pregnancy is substantiated. Human fetal membranes are appendages of placenta and compose of amnion, chorion and decidua tissues. They play a critical role as defensive barriers in order to maintain normal pregnancy. Recent in vitro studies have demonstrated that influenza A/H1N1 virus infection induced apoptosis and the gene expression of a set of pro-inflammatory cytokines, such as interleukin (IL)-6, tumor necrosis factor (TNF)-α and interferon (IFN)-β in cultured chorion cells. IL-6, TNF-α and IFN-β molecules in culture supernatants of the virus-infected chorion cells induced the differentiation of monocytes to well-matured macrophages. It should be noted that these phenomena were not observed in cultured amnion cells after influenza virus infection, yet viral replication was observed in the cells. It has been known that apoptosis of the constituent

Preface

ix

cells and macrophage activation in the tissues are implicated in the pathogenesis of fetal membrane rupture. Therefore, accumulating evidence suggests that fetal membrane chorion and amnion cells play a pivotal role in the pathogenesis of influenza-associated complications during pregnancy. This article reviews the virulence of influenza virus against human fetal membrane tissues in order to understand the molecular pathogenesis of intrauterine influenza virus infection during pregnancy. Chapter 4 - Bad obstetric history (BOH) implies previous unfavorable foetal outcome in terms of two or more consecutive spontaneous abortions, history of early neonatal death, intrauterine growth retardation, stillbirths, intrauterine fetal death and/or congenital anomalies. Recurrent pregnancy wastage due to maternal infections transmissible in utero at various stages of gestation can be caused by a wide array of organisms that include Toxoplasma gondii, rubella virus, cytomegalovirus, herpes simplex virus and other agents. Herpes simplex virus (HSV) is classified in the alpha virinae subfamily within the family Herpesviridae. Two closely-related viruses are designated HSV types 1 and 2. Both can be transmitted in utero to fetus, with more complications associated with herpes simplex 2. Another important viral cause of BOH is cytomegaloviruses (CMV). Cytomegaloviruses are ubiquitous and species-specific. Humans are believed to be the only reservoir of this virus, and transmission occurs by direct or indirect person-to-person contact. Vertical transmission can lead to serious congenital infections. Rubella virus causes serious disease after vertical transmission. Most maternal infections remain subclinical or cause a trivial infection that may remain unrecognized. Its vaccination coverage is not sufficient throughout the world, so new cases are still reported. Clinical diagnosis of rubella is difficult and unreliable, as rubella virus infection can be asymptomatic in up to 50% of infected patients. Several modalities are available for the diagnosis of those infections. The benchmark method is viral culture. Serology can establish current and past infection. Recently, molecular techniques have become available for rapid diagnosis. Testing of pregnant women for HSV, CMV and rbella antibodies is usually done with a type-specific assay for their antibodies. The objective of the present study was to explore the prevalence of herpes simplex virus 2, cytomegalovirus and rubella in pregnant with repeated spontaneous abortions (RSA) in first trimester. The diagnosis was performed by polymerase chain reaction, serological study for specific immunoglobulins G and M for herpes simplex 2 and cytomegalovirus and rubella. There was also an attempt to discover the accuracy of serological diagnosis for herpes simplex 2 and cytomegalovirus compared to polymerase chain reaction. Patients recruited in the study were complaining of repeated first trimester abortions without obvious medical or gynecological etiology. Laboratory screenings for immunoglobulin M for toxoplasmosis were negative. The study also included pregnant women with normal obstetric history as a control group. Complete medical and obstetric evaluations were performed for patients and control subjects. Furthermore, specific virological diagnosis was performed to measure specific immunoglobulins M and G for CMV and herpes simplex 2 by enzyme linked immunosorbant assay with detection of their DNA in maternal serum by polymerase chain reaction. Diagnosis of rubella was performed by measurement of specific immunoglobulin M by enzyme linked immunosorbant assay.

x

Richard N. Canfield

There was a statistically significant difference between the RSA group and the pregnant women without RSA in frequency of rubella IgM (44.7%), herpes simplex IgM (39.1%) and CMV 10.9% (P < .001) . However, there was insignificant difference in IgG for herpes simplex 2, CMV and rubella between patients and control. Herpes simplex 2 viremia was positive in 26% RSA and cytomegalovirus was positive in 10.9% RSA patients. There was a significant association between viremia for cytomegalovirus and herpes simplex 2 (P0.05

No

3.54

P>0.05

No

5(20.0)

16(64.3)

4(16.0)

25

3.04

≥11.0g/dl

19(16.4)

83(71.6)

14(12.1)

116

2.97

Total

24

99

18

141

Blood Group A

6(14.0)

30(69.8)

7(16.3)

43

3.04

B

2(6.5)

25(80.6)

4(12.9)

31

3.09

AB

0(0.0)

2(100.0)

0(0.0)

2

2.85

O

25(28.0)

68(63.6)

14(13.1)

107

2.98

Total

33

125

25

183

9(12.0)

59(78.7)

7(9.3)

75

2.97

AA

19(17.4)

72(66.1)

18(16.5)

109

2.98

Total

28

131

25

184

Genotype AS

Statistical Analysis . .

Prevalence Placental Malaria in Relation to Maternal Peripheral Malaria, Placental Weight, Neonatal Birthweight and Anthropometric Parameters A total of 278 placental blood samples were available for study, and of these, 34(12.2%) had malaria parasites of between 1-10 parasites per 100 thick film fields. Placental weight was determined for 214 placental samples. Neonatal birthweight was determined for 231 babies while the fetal length and fetal head circumference were determined for 195 and 190 babies respectively (Table 8).

Impact of Materno-Placental Malaria, Anaemia and HIV Infection…

261

Table 8. Association of placental malaria with maternal malaria, placental weight and fetal parameters in Abakaliki, south-eastern Nigeria Parameter

Number Examined

Number (%) with Infected placenta

Statistical Analysis . χ2 test

P value

Statistical Difference

94.4

P0.05

No

0.04

P>0.05

No

Maternal Malaria Infection Infected

48

26(54.2)

Uninfected

230

28(3.5)

Total

278

34(12.2)

30

10 (33.3)

Placental Weight (Kg) ≤ 0.4 0.5-0.7

164

21(12.8)

≥ 0.8

20

3(15.0)

Total

214

34(15.9)

Birthweight (Kg) 0.05). Women with peripheral malaria infection had babies with higher proportion of fetal anaemia (72.2%) compared with the uninfected women (64.2%), but the difference was not statistically significant (χ2 =1.97, df=1, P>0.05). Fetal anaemia prevalence was higher among babies born by anemic women (82.6%) than those of the non-anemic women (63.5%) but the difference was not statistically significant (χ2 =3.32, df=1, P0.05) (Table 9). Table 9. Association of fetal haemoglobin concentration (HbC) with maternal malaria Infection, anaemia and HIV infection among women at childbirth in the AbakalikiNigeria Maternal Parameters

Parity Primigravidae

Fetal HbC (g/dl) . No.(%) No.(%) 0.05

No

3.32

P>0.05

No

0.86

P>0.05

No

Malaria Infection Infected

HbC

HIV Status Positive Negative

134(65.5)

72(35.0)

206

Total

139(65.6)

73(84.4)

212

Impact of Materno-Placental Malaria, Anaemia and HIV Infection…

263

Discussion Effects of Malaria and HIV Infection on Maternal Parameters at Childbirth and on Birthweight Malaria and Age Individuals of the ≤19 years and 20-24 years age categories were more infected with malaria infection than other age groups categories, although the difference in the trend was not statistically significant. This observation supported previous findings from eastern Sudan (Adam et al. 2005) and in Kigali, Rwanda (Lander et al. 2002) which indicated that age was not significantly associated with malaria during pregnancy. In contrast however, a number of earlier studies reported a significant association between maternal age and malaria infection during pregnancy (Bouyou-Akotet et al. 2003; Rogerson et al. 2000). In a study conducted in Blantyre, Malawi, after stratifying by gravidity, associations between age and parasite prevalence were reportedly stronger than those between gravidity and prevalence after stratifying by age (Rogerson et al. 2000). The reason for the occurrence of these age-related differences in malaria prevalence may probably be related to host or environmental factors. Malaria and Parity The prevalence of malaria infection was higher among the primigravidae than the multigravidae, although the difference in the trend was not statistically significant. This finding is consistent with reports from other parts of the sub-Saharan Africa which have consistently indicated that primigravidae are more susceptible to malaria infection than the multigravidae probably because immune suppression is more marked in primigravidae and the protective immunity acquired through malaria infection during the first pregnancy, appears to reduce susceptibility in subsequent pregnancies (Mockenhaupt et al. 2000). Malaria and HIV Infection The women with HIV infection had a higher prevalence of malaria infection than those without HIV infection and the difference was statistically significant. Similar findings were reported in a number of sub-Saharan African countries including Malawi (Steketee et al. 1996), Zimbabwe (Ticconi et al. 2003), Kenya (van Eijk et al. 2003), and Rwanda (Lander et al. 2002). The reason for the higher prevalence of malaria infection among the HIV positive individuals may be due to the impairment of the ability of pregnant women to control P. falciparum infection, which was earlier demonstrated (ter Kuile et al. 2004), and the interference with the maintenance of immune recognition of malaria by HIV infection in pregnancy (van Eijk et al. 2003). Malaria and Anaemia In this study, anaemic women had higher prevalence of malaria infection than nonanaemic women. This was consistent with reports from a number of sub-Saharan African countries which indicated that the prevalence of anaemia was consistently higher among pregnant women infected with malaria parasites than those uninfected (Adam et al. 2005; Mockenhaupt et al. 2006). Individuals with no insecticide treated bed nets and those who

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C. J. Uneke, I. Sunday-Adeoye, F. E. Iyare et al.

never visited the ANC or attended ANC less than 5 times during pregnancy also had higher prevalence of malaria infection. In Kenya (Wabwire-Mangen et al. 1989) and Burkina Faso (Parise et al. 2003), similar results were reported. These findings underscore the importance of ANC attendance during pregnancy. It has been demonstrated that substantial reductions in maternal malaria, anaemia, and LBW have been achieved by intervention programs, including the use of ITNs, preventive intermittent treatment and chemoprophylaxis administered at the ANC (Parise et al. 2003; WabwireMangen et al. 1989). Interventions also exist for maternal anaemia (e.g., good nutrition, iron and folate supplementation, and hookworm treatment) and these have been provided through antenatal care programs. In fact, studies from sub-Saharan Africa have suggest that between 25% and 90% of these adverse events might be prevented by full implementation of existing interventions at the ANC (Miaffo et al. 2004).

Low Birth Weight in Relation to Maternal Malaria and Parity In this study, statistical analysis showed that low birth weight (LBW) was associated with maternal malaria infection, although babies born by infected mothers had a lower mean birth weight and higher prevalence of LBW compared to the uninfected mothers. This indicates that other factors aside from malaria could also be playing major roles in the determination of low birth weight in the study population. The prevalence of LBW was higher among babies born by primigravidae than the multigravidae and the difference was statistically significant (P0.05). This is similar to the findings in northern Zimbabwe (Ticconi et al. 2003), where HIV infection was independently associated with increased risk of low birth weight (OR = 3.16, 95% CI: 1.80-5.54) and very low birth weight (OR = 10.74, 95% CI: 2.12-54.41). Furthermore, in Kigali, Rwanda, it was observed that the frequencies of low birthweight, prematurity, and intrauterine growth retardation were higher in infants born to HIV positive women than to HIV negative women (Castetbon et al. 1999). In yet another study conducted in Kigali, Rwanda, low birth weight was significantly more frequent in fullterm infants born to HIV-positive mothers than to HIV-negative mothers (Leroy et al. 1994). These results underscore the need for nutritional surveillance and dietary counseling, hoping to improve the prognosis of pregnancy in HIV positive women, regardless of other therapeutic interventions.

Low Birth Weight and ANC Attendance It was noted in this study that a very high proportion of LBW occurred among babies born by women who did not attend the antenatal clinic and the prevalence of LBW reduced with increase in the number of antenatal clinic visits. This finding clearly demonstrates the efficacy of antimalarial chemoprophylaxis and haematenics which are usually administered during ANC in the prevention of malaria and anaemia and improvement of neonatal birth weight. Despite the non statistically significant difference observed in the trend, this finding supported earlier reports from The Gambia where the birth weight of children born to women who received chemoprophylaxis was increased by an average of 153 g (Menendez et al. 1994). In another related study the administration of chemoprophylaxis led to a reduction in the prevalence of low birth weight babies and to an increase in the median birth weight and the perinatal mortality rate was lower, although not significantly so, among the babies of women who had received chemoprophylaxis (Greenwood et al. 1994). Furthermore in a study in rural Malawi (Steketee et al. 1996), it was noted that the use of an effective antimalarial was protective against LBW through its effect on reducing placental

266

C. J. Uneke, I. Sunday-Adeoye, F. E. Iyare et al.

and umbilical cord blood malaria infection. The study concluded that effective prevention of malaria in pregnant women in malaria-endemic settings may reduce the likelihood of LBW by 5-14%, and may reduce the amount of preventable LBW by more than 30%. Therefore, when evaluating antenatal care programs, health policy makers must consider providing an effective preventive drug as a means to prevent low birth weight and its consequences.

The Relationship between Maternal Malaria, Demographic Parameters, ABO Blood Group, Genotype and Birth Weight at Childbirth Malaria and Demographic Parameters Although lower literacy level and younger age were more predisposing factors to malaria infection in this study, the differences in the trend were however not statistically significant. However, occupation was significantly associated with malaria infection but the reason for this outcome was somewhat obscure. Previous findings from eastern Sudan (Adam et al. 2005) and Kigali, Rwanda (Lander et al. 2002) had indicated that age was not significantly associated with malaria during pregnancy and the report of an investigation from Zanzibar, Tanzania, showed no apparent relationship between malaria and socio-demographic parameters including occupation (Matteelli et al. 1994). Malaria and Genotype The prevalence of malaria infection in this study was higher among individuals with HbAA genotype than those with HbAS genotype but the difference was not statistically significant (P>0.05). Although studies that investigated this relationship between malaria and haemoglobin genotypes in pregnancy are essentially lacking, malaria has been shown to be consistently higher in non-pregnant individuals with HbAA genotype compared to those with HbAS (Eteng, 2002). The sickle cell trait (HbAS) has been shown to confers a high degree of resistance to severe and complicated malaria (Aluoch, 1997; Aidoo, 2002), but the mechanisms by which the hemoglobin genotype HbAS protect against severe malaria are not fully understood. The greater susceptibility of HbAA individuals to P. falciparum malaria and the enhanced severity of an attack in this group may be due to low red cell membrane resistance to the invading parasite and a non-hypoxic environment within the red cell which enhances its development (Eteng, 2002). Furthermore, results from a study that evaluated the immune basis for malaria protection by the sickle cell trait in Kenya suggested that malaria protection by HbAS involves the enhancement of not only innate but also of acquired immunity to the parasite and indicated that a better understanding of the underlying mechanism might yield important insights into both these processes (Williams et al. 2005). Malaria and ABO Blood Group The highest prevalence of malaria infection in the present investigation was recorded among women with blood group O. Studies evaluating the relationship between malaria and ABO blood group during pregnancy are also essentially lacking. The only current study related to this was the evaluation of the ABO phenotypes and malaria outcomes in mothers and babies in The Gambia (Loscertales and Brabin, 2006). In that study, blood group O was associated with an increased prevalence of active placental infection in primiparae and with a

Impact of Materno-Placental Malaria, Anaemia and HIV Infection…

267

reduced risk of placental malaria in multiparae. Placental parasitaemia was observed to occur at least twice as frequently in primiparae but only among blood group O women. More systematic studies are urgently needed to further elucidate this. Low Birth Weight in Relation to Blood Group and Genotype In this investigation maternal malaria infection was not significantly associated with birth weight, although infected mothers had a higher proportion of low birthweight (LBW) babies than the uninfected mothers. Similarly, none of the haematological parameters investigated indicated any significant association with birthweight. The proportion of LBW babies were higher among anaemic women, those with blood group O and individuals of the HbAA genotype. The reason for this outcome could not be clearly ascertained, however it is interesting to note that individuals who belong to these categories had higher prevalence of malaria infection. Therefore these results suggest that maternal malaria may be the major determining factor to LBW in this study and that the haematological parameters may have played only a secondary role in the LBW observed. Falciparum malaria during pregnancy has long been recognized as an important determinant of low birth weight (Brabin, 1991; Menendez et al. 1995) and a number of randomized controlled trials of preventive antimalarial measures during pregnancy have confirmed this causal effect by showing that preventing malaria increases birth weight (Cot et al. 1995; Menendez et al. 1994).

Placental Malaria and Its Relationship with Perinatal Outcome Prevalence of Placental Malaria Placental infection measured by placental smear at delivery has been described as a standard indicator, which is widely used to characterize malaria infection in pregnant women (Cottrell et al. 2005). Using this technique, a placental P. falciparum malaria prevalence of 12.2% was obtained in this study. Placental malaria prevalence results from various parts of sub-Saharan Africa have been discordant, and one of the major factors in the discordance is that different techniques of diagnosis of employed based on the differences in the definition of placental malaria (Othoro et al. 2006). Using the placental blood smear microscopy, placental malaria prevalence rates of 9.5%,18.5%,19.9%, and 37.1% were obtained in Senegal (N’Dao et al. 2006), Sierra Leone (Morgan, 1994), Cameroon (Tako et al. 2005), and Gambia (Okoko et al. 2002) respectively. These results indicate that placental malaria is still unacceptably high in the sub-Saharan Africa and calls for the intensified efforts in malaria control in pregnancy. The importance of effective control measures cannot be overstated because apart from the adverse perinatal outcomes associated with placental malaria, some studies also suggest that children born to mothers with placental malaria are at a high risk of acquiring larger numbers of P. falciparum infections in the first 2 years of life compared to infants born to women without placental malaria (Van Eijk et al. 2003). Furthermore, it was reported that placental malaria infection diminished the development of antibody responses to malarial epitopes in the first year of

268

C. J. Uneke, I. Sunday-Adeoye, F. E. Iyare et al.

life, the age at which most of the severe malaria-associated morbidity occurs in areas of holoendemicity (McElroy et al. 1999). Placental Malaria and Maternal Peripheral Malaria In this study maternal peripheral malaria infection was significantly associated with placental malaria (P