Seasonality of birth outcomes in rural Sarlahi District, Nepal: a population-based prospective cohort

Abstract

BackgroundWhile seasonality of birth outcomes has been documented in a variety of settings, data from rural South Asia are lacking. We report a descriptive study of the seasonality of prematurity, low birth weight, small for gestational age, neonatal deaths, and stillbirths in the plains of Nepal.MethodsUsing data collected prospectively during a randomized controlled trial of neonatal skin and umbilical cord cleansing with chlorhexidine, we analyzed a cohort of 23,662 babies born between September 2002 and January 2006. Project workers collected data on birth outcomes at the infant’s household. Supplemental data from other studies conducted at the same field site are presented to provide context. 95% confidence intervals were constructed around monthly estimates to examine statistical significance of findings.ResultsMonth of birth was associated with higher risk for adverse outcomes (neonatal mortality, low birthweight, preterm, and small for gestational age), even when controlling for maternal characteristics. Infants had 87% (95% CI: 27 – 176%) increased risk of neonatal mortality when born in August, the high point, versus March, the low point.ConclusionSeasonality of neonatal deaths, stillbirths, birth weight, gestational age, and small for gestational age were found in Nepal. Maternal factors, meteorological conditions, infectious diseases, and nutritional status may be associated with these adverse birth outcomes. Further research is needed to understand the causal mechanisms that explain the seasonality of adverse birth outcomes.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2393-14-310) contains supplementary material, which is available to authorized users.

Linear trends and seasonality of births and perinatal outcomes in Upper East Region, Ghana from 2010 to 2014

“…Data from Nepal showed that the highest preterm birthing corresponded to high temperature exposures [37], possibly due to greater risk of labour induction as a result of decreased uterine blood flow when dehydration sets in [38]. On the other hand, the low birthing during the dry season can be attributed to increased risk of infection such as malaria during the rainy season.…”

A Comparative Study of Food Consumption and Nutritional Status of Women in West Bengal

“…Lawlor et al (2005) reported that the birth weight was seasonally patterned in Aberdeen, Scotland, with LBWs among those born in the winter months and highest birth weights among those born in the autumn months. A similar study has reported that newborn born in the fall had a significantly lower birth weight than those born in the winter (Onyiriuka 2006;Chodick et al 2007;Strand et al 2012;Hughes et al 2014;Zhang et al 2017), indices that the extremes of temperature may be an important determinant of LBW. Onyiriuka (2006) has reported that the mean birth weights significantly differed between wet and dry seasons in newborns born in Nigeria (p<0.01).…”

“…The analysis of seasonal variations in birth weights may enable researchers to suggest specific factors that influence the measure of LBW (McGrath et al 2005;Chodick et al 2007;Hughes et al 2014;Lei et al 2016;Zhang et al 2017). Maternal exposure to the lower outdoor ambient temperature in mid-trimesters can also lead to an increase in LBW (Strand et al 2012).…”

“…Significant number of studies have reported effects of maternal age and pregnancy order with newborn birth weight (Badshah et al 2008;Elshibly and Schmalisch 2008;Christian 2009;Bisai 2010;Sen et al 2010;Adane et al 2014;Demelash et al 2015;Mahumud et al 2017;Wang et al 2017). It has also been reported that a wide range of LBW-related morbidity/mortality is influenced by the external environment such as temperature, humidity and rainfall throughout the seasons (Murray et al 2000;Lawlor et al 2005;Onyiriuka 2006;Chodick et al 2007;Strand et al 2012;Hughes et al 2014;Lei et al 2016;Zhang et al 2017). Infants born during late spring and summer are lighter than those born in winter, which might result from exposure to low winter temperatures during mid-gestation (Murray et al 2000).…”

Human Metapneumovirus and Other Respiratory Viral Infections during Pregnancy and Birth, Nepal

“…Overall, the observed incidences of LBW and PTB in this cohort were slightly lower than previous estimates in the region, reflecting an overall improvement in health in the population. Among all women enrolled, 25% gave birth to an LBW infant, compared with 30.4% in previous studies; 13% gave birth preterm, compared with 18.3% in previous studies (15,39). In the parent trial of maternal influenza immunization, influenza vaccination during pregnancy was effective in prevention of influenza infection in infants and was also associated with increased birthweight (20).…”