Discussion
malaria, deaths, prematurity
MALARIA, MISCARRIAGES, NAIROBI
Our data complements that reported by INTERGROWTH-21st, in that our Kenyan subjects were recruited from a rural agricultural setting with a significant malaria burden, whereas the Kenyan subjects in the INTERGROWTH-21st trial were recruited from the Parklands area of suburban Nairobi. Parklands is considered a middle to upper socioeconomic urban area, while the area of our study is largely defined as a World Bank rural poverty area. Thus, our population demographics are considerably different than those of the Kenyan subjects included in the INTERGROWTH-21st study. Despite these in-country geographical variations, our results, from rural Western Kenya, are quite similar to those reported for INTERGROWTH-21The incidence of prematurity and low birth weight are important public health indicators for a population. In addition, the construction of birth weight percentiles for gestational age are crucial for establishing the intrauterine growth of an infant, which is then used to track postnatal growth. Abnormal postnatal growth, as evidenced by deviations from the expected weight for age percentile that are established by the assessment of birth weight for gestational age, is then used as a warning sign for the need for nutritional intervention. However, it is known that the birth weight distribution curve varies among populations. In addition, despite extensive study, it has been challenging for clinicians and public health practitioners to find accurate prenatal surrogate markers that correlate reliably with actual birthweight [Birth weight and gestational age are intertwined, and it is crucial in evaluating a population to be able to separate low birth weight due to prematurity and low birth weight due to fetal factors, either constitutional or nutritional. Therefore, fetal growth curves with accurate birth weights are important tools for evaluating public health interventions designed to reduce rates of stillbirth [The INTERGROWTH-21st study found that for most gestational weeks, median birthweights differed for male and female infants. The signed rank test used for this analysis was performed separately for male and female data but was limited by sample size disparities. Although this analysis had limitations and was based on a single metric (median), the observed significant differences at lower gestational ages for females and higher gestational ages for males warrant further investigation in the rural, western Kenyan population. A major strength of our cohort is the data originated from a prospectively designed study. Subjects were enrolled early in pregnancy as part of the ASPIRIN trial, and tracked prospectively through delivery to 42 days postpartum, as part of our established, population-based maternal newborn health registry, which employs rigorous quality assurance procedures [In the present study, another strength was our very low loss-to-follow up rate; we lost only 22 subjects (1.56%) to follow-up before birth. Another key strength is the rigorous quality-assurance standards that were utilized to train, monitor, and evaluate the sonographers in this study [There are several limitations of our study. First, the sample size is relatively small, especially for infants born below 36 weeks and of less than 2500 g. Furthermore, we used data only from women who had qualified for and enrolled in the ASPIRIN study, as these women all had accurate ultrasound gestational dating. This limited our subjects to primagravidas, and to singleton pregnancies, consistent with the ASPIRIN eligibility requirements. It is well established that multiple gestation pregnancies are more likely to result in low birthweight infants. Birth spacing can also impact the birthweights of subsequently born sibling infants, as compared to first born infants [Similar to challenges faced by other groups (e.g., EN-INDEPTH; Blencowe, et al., 2021) [As mentioned previously, we had a very low loss-to-follow-up rate, overall. However, an additional 93 subjects, while not lost to follow-up, did not have measured birth weights. Of these, 49 pregnancies ended before 20 weeks and were considered miscarriages. Of the remaining subjects, 27 were stillbirths, 5 were neonatal deaths, and 12 had unknown status. A final challenge faced in this study is the limited precision of the scales used to determine birth weights. In general, these scales were graduated at 50-g increments. Combined with documented “digit preference” bias from other settings, including within the East African region [