The conception rate in Baroda and Manipal, India, is lowest during the hottest weather. The greatest extremes are found in Baroda and, following high summer temperatures, there is a prolongation of low conception rates which may indicate that part or all of the effect is mediated through an effect on scrotal temperature. However, other factors may also be involved and a reduction of coital frequency is likely at extremes of temperature. Seasonal changes in abortion, stillbirths and prematurity are also observed. Changes in spontaneous abortion could be due to heat stress in the mother or possibly to abnormal sperm production at high temperature or to less frequent coitus, leading to embryonic defect
