Boon Lim1,2, Associate Professor
Department of Obstetrics and Gynaecology, Canberra Health Services, Canberra, Australia
Australian National University
As the impacts of climate change continue to accelerate, there has been an exponential rise in the number of natural disasters, with flooding playing a significant role. Over the last 50 years there has been a five-fold increase in the number of floods, with flooding contributing to 44% of all natural disasters (World Meteorological Organisation.Weather-related disasters increase over past 50 years, causing more damage but fewer deaths , 2021). Developing countries are particularly vulnerable to the effects of these natural disasters, which contribute to direct health implications as well as significant disruptions to access to health care. Data surrounding the impacts of climate change on health outcomes has grown, revealing a growing field of literature examining the negative impacts of flooding on reproductive outcomes.
Multiple direct and indirect factors contribute to poor reproductive health outcomes following flooding events. Flood waters lead to poor water quality as well as an increase in infectious diseases. Displacement of large numbers of people, particularly in developing countries, leads to overcrowding in emergency accommodation and subsequently increased rates of communicable diseases. Furthermore, damage to health infrastructure and limited access to health facilities impact women’s ability to seek pregnancy care (UK AID. Foreign, Commonwealth and Development Office. The effects of floods on access to sexual and reproductive health and family planning in Pakistan , 2023). The physical and psychological stressors experienced by women affected by floods are hypothesised to contribute to the higher rates of gestational hypertension, preeclampsia and babies with low birth weights (Partash et al. Taiwan J Obstet Gynecol 2022; 61:10-4). These effects are compounded in lower socioeconomic areas, particularly developing countries with already limited resources. Following recent floods in Pakistan, over 8 million people were displaced; only 29% of women in displacement camps have received counselling on pregnancy care and 19% have received delivery kits (UK AID, 2023).
There have also been studies evaluating the influence of environmental factors on the sex ratio (the ratio of males to females in a population) of live births. Anaesthetic gases, air pollution and times of flooding have all been shown to impact sex ratio of deliveries in affected populations. Following floods in Brisbane, Australia there was a noticeable reduction in the sex ratio, thought to be linked to a reduction of the hardness and pH in the drinking water. The change in sex ratio is hypothesised to be due to the sensitivity of the Y-bearing spermatozoa to dietary changes during the meiotic stages of spermatogenesis, which occurs approximately 7 weeks prior to arrival of the ejaculate (Lyster & Bishop. J. Reprod. Fertil, 1965;10:35-47). This effect of flooding is further supported by the seasonal trend noted in the sex ratio, which is related to the level of precipitation approximately 10-11 months prior to birth (Lyster.BJOG , 1974;81:626-631) (Fig.1).
With flooding becoming increasingly prevalent throughout the world, it is clear that the focus needs to shift to providing affected communities by reducing barriers to accessing care, particularly antenatal care. Careful planning is required to ensure improved access to care, water quality and reduce overcrowding to reduce pregnancy complications and better health outcomes of children globally.
Figure 1.