Prevalence of congenital microcephaly and its risk factors in an area at risk of Zika outbreaks

Songying Shen,Wanqing Xiao,Si Tu,Jinhua Lu,Jia Yu,Anna Funk,Jianrong He,Arnaud Fontanet,Xiu Qiu,Li Yang,Wei Bao,Kar Keung Cheng,Lifang Zhang

doi:10.1186/s12884-021-03705-9

Abstract

BackgroundPrevalence of neonatal microcephaly in populations without Zika-epidemics is sparse. The study aimed to report baseline prevalence of congenital microcephaly and its relationship with prenatal factors in an area at risk of Zika outbreak.MethodsThis study included singletons born after 24 gestational weeks in 2017–2018 at four hospitals in Guangzhou, China. Microcephaly was defined as a head circumference at birth >3SD below the mean for sex and gestational age. Prevalence of microcephaly was estimated by binomial exact method. Multivariable logistic regression was used to examine the associations of microcephaly with prenatal factors. The population attributable fraction (PAF) for associated risk factors was calculated.ResultsOf 46,610 live births included, 154 (3.3, 95% CI 2.8–3.9 per 1000 live births) microcephalies were identified. Maternal hepatitis B virus carriers (HBV, OR 1.80, 95% CI 1.05–3.10) and primipara (OR 2.68, 95% CI 1.89–3.81) had higher risk of having a microcephalic baby. Higher prevalence of microcephaly was observed in women who had premature labor (OR 1.98, 95% CI 1.17–3.34) and had a baby with fetal growth restriction (OR 16.38, 95% CI 11.81–22.71). Four identified factors (HBV, primiparity, preterm labor, and fetal growth restriction) contributed to 66.4% of the risk of microcephaly.ConclusionsThe prevalence of microcephaly in Guangzhou was higher than expected. This study identified four prenatal risk factors that, together, contributed to two-thirds of the increased risk of microcephaly. This is the first reported association between maternal HBV carrier status and microcephaly.

Highlights

Prevalence of neonatal microcephaly in populations without Zika-epidemics is sparse
After excluding newborns with unknown sex (n = 3) and missing (n = 328) or implausible head circumference (HC) data (n = 145), stillbirths (n = 222), and those with brain and central nervous system (CNS) abnormalities (n = 25) and/or chromosome abnormalities (n = 36), 46,610 newborns were included in the final analysis
There were 154 newborns identified with microcephaly across all births, with a prevalence of 3.3

Summary

Introduction

Prevalence of neonatal microcephaly in populations without Zika-epidemics is sparse. The study aimed to report baseline prevalence of congenital microcephaly and its relationship with prenatal factors in an area at risk of Zika outbreak. An understanding of the maternal and neonatal factors related to microcephaly at birth is likely to facilitate early identification of microcephaly and effective intervention. Well-known causes of microcephaly include maternal infections, such as Zika virus and cytomegalovirus, genetic factors, and teratogens. These understandings are mainly based on evidence from recent Zikaepidemic areas [8,9,10]. The epidemiology of microcephaly in populations without an outbreak of Zika virus infection is poorly described. In spite of the evidence above, the epidemiology of different subtypes of microcephaly remains largely unknown

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