Adverse birth outcomes and their clinical phenotypes in an urban Zambian cohort
Joan T Price1,2,3, Bellington Vwalika2, Katelyn J Rittenhouse1
1Division of Global Women's Health, Department of Obstetrics and Gynecology, University of North Carolina, School of Medicine, Chapel Hill, NC, USA.
Insights
This study in Zambia found high rates of preterm birth, small-for-gestational-age, and stillbirth. Key risk factors included prior preterm birth, short cervix, twins, and antenatal hypertension, highlighting the need for better data in low-resource settings.
Area of Science:
- Obstetrics and Gynecology
- Maternal and Child Health
- Public Health in Sub-Saharan Africa
Background:
- Limited rigorous cohort studies in sub-Saharan Africa hinder understanding of adverse birth outcomes.
- Inadequate gestational age dating and clinical phenotyping complicate risk factor identification.
Purpose of the Study:
- To investigate adverse birth outcomes in urban Lusaka, Zambia.
- To characterize incidence and risk factors for preterm birth, small-for-gestational-age, and stillbirth.
Main Methods:
- Prospective observational cohort study (Zambian Preterm Birth Prevention Study - ZAPPS) from August 2015 to September 2017.
- Follow-up through 42 days postpartum with standardized assessment of neonatal outcomes and delivery phenotypes.
- Primary outcomes: preterm birth (<37 weeks), small-for-gestational-age (<10th percentile), and stillbirth.
Main Results:
- 15% preterm birth, 18% small-for-gestational-age, and 4% stillbirth among 1216 deliveries.
- Risk factors for preterm birth included prior preterm birth, short cervix, twins, and antenatal hypertension.
- Small-for-gestational-age associated with twins and antenatal hypertension; stillbirth associated with short cervix.
Conclusions:
- High rates of preterm birth, small-for-gestational-age, and stillbirth confirmed in Lusaka, Zambia.
- Accurate gestational age dating and data ascertainment are crucial for understanding adverse birth outcomes in low-resource settings.
- Identified risk factors provide targets for intervention and prevention strategies.
Abstract:
Background: Few cohort studies of pregnancy in sub-Saharan Africa use rigorous gestational age dating and clinical phenotyping. As a result, incidence and risk factors of adverse birth outcomes are inadequately characterized. Methods: The Zambian Preterm Birth Prevention Study (ZAPPS) is a prospective observational cohort established to investigate adverse birth outcomes at a referral hospital in urban Lusaka. This report describes ZAPPS phase I, enrolled August 2015 to September 2017. Women were followed through pregnancy and 42 days postpartum. At delivery, study staff assessed neonatal vital status, birthweight, and sex, and assigned a delivery phenotype. Primary outcomes were: (1) preterm birth (PTB; delivery <37 weeks), (2) small-for-gestational-age (SGA; <10 th percentile weight-for-age at birth), and (3) stillbirth (SB; delivery of an infant without signs of life). Results: ZAPPS phase I enrolled 1450 women with median age 27 years (IQR 23-32). Most participants (68%) were multiparous, of whom 41% reported a prior PTB and 14% reported a prior stillbirth. Twins were present in 3% of pregnancies, 3% of women had short cervix (<25mm), 24% of women were HIV seropositive, and 5% were syphilis seropositive. Of 1216 (84%) retained at delivery, 15% were preterm, 18% small-for-gestational-age, and 4% stillborn. PTB risk was higher with prior PTB (aRR 1.88; 95%CI 1.32-2.68), short cervix (aRR 2.62; 95%CI 1.68-4.09), twins (aRR 5.22; 95%CI 3.67-7.43), and antenatal hypertension (aRR 2.04; 95%CI 1.43-2.91). SGA risk was higher with twins (aRR 2.75; 95%CI 1.81-4.18) and antenatal hypertension (aRR 1.62; 95%CI 1.16-2.26). SB risk was higher with short cervix (aRR 6.42; 95%CI 2.56-16.1). Conclusio ns: This study confirms high rates of PTB, SGA, and SB among pregnant women in Lusaka, Zambia. Accurate gestational age dating and careful ascertainment of delivery data are critical to understanding the scope of adverse birth outcomes in low-resource settings.
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