Associations of climatic factors with pregnancy loss in Nicosia, Cyprus

Background: While ambient climatic factors are linked to adverse pregnancy outcomes, only a few studies examine the risk of pregnancy loss. Objective: This study aims to examine the effects of climatic factors on pregnancy loss in Nicosia, Cyprus, an area that is highly affected by climate change. Methods: Birth registry data obtained from maternity units in Nicosia from 2014–2019 were linked with daily meteorological and traffic pollution data (minimum and maximum temperature, °C; relative humidity [RH], %; and nitrogen dioxide [NO₂], μg/m³). We also estimated other climatic factors from the obtained data (mean weekly temperature, standard deviation of weekly temperature and RH [temperature and RH variability], and heat index [HI]). We used a novel variation of time-series design and distributed lag models adjusting for secular trends and air pollution to explore the association between climatic factors and weekly live-birth identified conceptions (LBICs), to indirectly estimate pregnancy losses. Results: There were 26,382 live births over the study period, with an average weekly LBICs of 84.7(± 12.2). We found an association between exposure to higher temperature between gestation weeks 0–9 and pregnancy loss, with the strongest association in weeks 0–1. Specifically, for a 5°C increase in mean week 0–1 temperature, 3.17 (95% Confidence Interval [CI]: 1.06–5.28) additional conceptions would result in pregnancy losses. A similar effect during early pregnancy was found for exposure to minimum and maximum temperature, HI, and RH. Furthermore, we found that temperature variability may have an impact in later weeks during pregnancy, with the strongest estimate in week 26 (6.70 [95% CI: 0.78–13.21] losses per 5 °C increase in standard deviation of weekly temperature). Similar results were observed for RH variability. Impact Statement: This research investigates the link between climatic factors and pregnancy loss in Nicosia, Cyprus, a region experiencing rising temperatures and humidity levels. By analyzing live birth data using a novel time-series approach, the study finds that higher temperatures and humidity levels are associated with increased pregnancy loss, particularly in early gestation. These findings underscore the need for targeted public health interventions, such as heat warning systems, to mitigate the impact of climate change on vulnerable populations. As climate change escalates, understanding these associations is crucial for developing effective strategies to protect maternal and fetal health. (Figure presented.)