Abstract
BackgroundNulliparity has been associated with lower birth weight (BW) and other adverse pregnancy outcomes, with most of the data coming from high-income countries. In this study, we examined birth weight for gestational age z-scores and neonatal (28-day) mortality in a large prospective cohort of women dated by first trimester ultrasound from multiple sites in low and middle-income countries.MethodsPregnant women were recruited during the first trimester of pregnancy and followed through 6 weeks postpartum from Maternal Newborn Health Registry (MNHR) sites in the Democratic Republic of Congo (DRC), Guatemala, Belagavi and Nagpur, India, and Pakistan from 2017 and 2018. Data related to the pregnancy and its outcomes were collected prospectively. First trimester ultrasound was used for determination of gestational age; (BW) was obtained in grams within 48 h of delivery and later transformed to weight for age z-scores (WAZ) adjusted for gestational age using the INTERGROWTH-21st standards.Results15,121 women were eligible and included. Infants of nulliparous women had lower mean BWs (males: 2676 gr, females: 2587 gr, total: 2634 gr) and gestational age adjusted weight for age z-scores (males: − 0.73, females: − 0.77, total: − 0.75,) than women with one or more previous pregnancies. The largest differences were between zero and one previous pregnancies among female infants. The associations of parity with BW and z-scores remained even after adjustment for maternal age, maternal height, maternal education, antenatal care visits, hypertensive disorders, and socioeconomic status. Nulliparous women also had a significantly higher < 28-day neonatal mortality rate (27.7 per 1,000 live births) than parous women (17.2 and 20.7 for parity of 1–3 and ≥ 4 respectively). Risk of preterm birth was higher among women with ≥ 4 previous pregnancies (15.5%) compared to 11.3% for the nulliparous group and 11.8% for women with one to three previous pregnancies (p = 0.0072).ConclusionsIn this large sample from diverse settings, nulliparity was independently associated with both lower BW and WAZ scores as well as higher neonatal mortality compared to multiparity.
Highlights
Nulliparity has been associated with lower birth weight (BW) and other adverse pregnancy outcomes, with most of the data coming from high-income countries
In addition to maternal age, associations for risk of adverse pregnancy outcomes have been found with parity for maternal height, maternal education, number of antenatal care visits and for newborn sex [8, 9]
BW was obtained in grams and later transformed to z-scores adjusted for gestational age using the INTERGROWTH-21st standards [https://intergrowth21.tghn.org/]
Summary
Nulliparity has been associated with lower birth weight (BW) and other adverse pregnancy outcomes, with most of the data coming from high-income countries. We examined birth weight for gestational age z-scores and neonatal (28-day) mortality in a large prospective cohort of women dated by first trimester ultra‐ sound from multiple sites in low and middle-income countries. Neonates born to nulliparous women are reported to be at higher risk of death and other adverse outcomes, including low BW, being small for gestational age, and prematurity [5, 6]. Neonates born to multiparous women have been found to have higher BWs and better weight gain during infancy [10]. These positive effects have been limited to the second or third pregnancies and are associated with younger maternal age. Women with parity over three and age 35 or older have been found to have higher odds of adverse outcomes in low and middle-income settings [7]
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