Association of parity with birthweight and neonatal death in five sites: The Global Network’s Maternal Newborn Health Registry study
Background
The Maternal Newborn Health Registry (MNHR) is a prospective, population-based registry of pregnancies and deliveries conducted under the auspices of the Global Network for Women’s and Children’s Health Research (GN), a multi-country research network funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). The primary purpose of the MNHR is to quantify and analyze trends in pregnancy outcomes over time.
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. A meta-analysis that reviewed data from Asia, Africa and Latin America found that these risks were highest among nulliparous women under 18 years of age in comparison to women with one or two previous pregnancies between 18 and 35 years of age. 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.
Neonates born to multiparous women have been found to have higher BWs and better weight gain during infancy. However, 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.
The higher risks that infants of nulliparous women face may be associated with factors related to immaturity of the mother: incomplete growth, small size of the uterus and fetal competition for nutrients. Although the exact mechanisms are not clear, it seems that the first pregnancy “primes” the body for subsequent ones.
In this paper, our aim is to determine the association between parity and BW among women in five research sites of the MNHR. Because of its cohort design, large sample size, multiple sites and the quality of the data (including gestational age dating with first trimester ultrasound, implemented broadly in 2017), the MNHR has the potential to extend the current knowledge of the importance of parity on fetal growth and other offspring outcomes.
By: Garces A, Perex W, Harrison M, Hwang KS, Patel A, Nolen T et al.