Adverse Weather Conditions can have Negative Effects on Birth Outcomes: Evidence from a birth registry cohort in Tanzania

Climate change is bound to have particularly serious implications for public health in the least developed countries. Based on unique registry data from the Kilimanjaro Christian Medical Centre in Tanzania from 2001-2015, we aimed to investigate whether pregnancy exposure to weather conditions affects neonatal birthweight, length, head circumference, and Apgar scores and to evaluate changes in weather conditions across the studied period. Methods: N=30,068 pregnant women were assessed through a postpartum interview whereas baby data were obtained through medical records. Environmental data - rainfall, temperature, the multivariate ENSO index (MEI), the effective drought index, and harvest - were obtained through the Kilimanjaro International Airport weather station and examined during pregnancy and a preconception trimester. Our main analytical strategy was hierarchical regression analyses. Results: Analyses revealed a median birthweight of 3,185 g (IQR:600), a mean length of 49 cm (IQR:71) and a mean head circumference of 34 cm (IQR:24). Lower birthweight was associated with consecutive days with temperatures >30°C ( B -.01, CI95% -.00 - .05) in the third gestational trimester, poor harvest ( B -.13, CI95% -.10 -.08) and the interaction between insufficient rain and poor harvest ( B .20, CI95% .13 -.26). Shorter length was significantly associated with more days with temperatures >30°C at preconception ( B -.01, CI95% -.00 - .04) and in all gestational trimesters (range: B -.01 - -.02, CI95% - .00 - -.06). Smaller head circumference was associated with more consecutive days with temperatures >30°C at preconception ( B -.01, CI95% -.00 - .03) and with MEI ( B -.01, CI95% -.01 - .05) in the first trimester. Conclusions: Overall, exposure to adverse weather during pregnancy is associated with more negative birth outcomes. Therefore, climate change adaptation efforts should pay greater attention to limiting pregnant women’s exposure to adverse weather. What is already known on this topic What this study adds How this study might affect research, practice or policy ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement the study was funded by Department of Psychology UZH, Chair of Clinical Psychology and Psychotherapy ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The ethics protocol for this study was given ethical approval by The National Institute for Medical Research (NIMR/HQ/R.8a/Vol. IX/2587) and by the Kilimanjaro Christian Medical College Research Ethics. The Ethics Committee of the Faculty of Arts, University of Zurich, also gave ethical approval (Nr.17.8.8). A data transfer agreement between the Kilimanjaro Christian Medical College and the University of Zurich was signed in November 2017. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced during the current study are available from the corresponding author on reasonable request.