Demographic Predictors of Gestational Age at Delivery among Women of Ijaw Tribe in Bayelsa State, in the Niger Delta Region in Nigeria

Background: Though most pregnant women tend to deliver around their expected date of confinement, quite a significant number deliver preterm and postterm. The variation of delivery timing can result from obstetrics complications, genetic or demographic factors.

Objective: The objective of this study is to determine the influence of demographic factors of pregnant Ijaw women on gestational age at delivery, like: maternal age, parity, occupation, educational level, gestational age at booking, maternal height, and body mass index, on gestational age at delivery. It also intends to determine the effects of birth weight and fetal sex.

Materials and Methods: It was an observational cross-sectional study of 1484 booked pregnant women of Ijaw ethnic group, who delivered in the labour ward of the Niger Delta University Teaching Hospital. Their case notes were retrieved and relevant information such as maternal age, parity, educational level, and occupation was obtained. Others include maternal height and weight at booking, gestational age at booking, gestational age at delivery and birth weight. Body mass index was calculated from height and weight and categorized. Data was analyzed with Chi square, Pearson’s correlation coefficient, simple linear regression, and multivariate analysis

Results: The prevalence of preterm birth (PTB) among Ijaw women was 9.7%, and the prevalence of PTB was significantly associated with underweight, Odd ratio = 7.79[3.12, 19.50], low educational level, Odd ratio =2.27[1.40, 3.68], and late booking for antenatal care P = 0.004. Delivery postterm was significantly associated with class 1 obesity, Odd ratio =16.0[4, 59, 55.8], and delivery of male babies Odds ratio = 6.76[2.41, 18.96].

Demographic factors from multivariate analysis could only account for 15.9% of the factors responsible for gestational age at delivery, of which the most important were birth weight, educational level and maternal height at booking.

Conclusion: Though maternal and fetal demographic factors significantly affects birth weight, the bulk of the determinants (84.1%) are outside these factors, and it could be from obstetrics, genetic, or other factors.