'Conception origin' versus 'ambient outdoor temperature throughout pregnancy' in relation to offspring birthweight - Reply

Authors' Reply Sir, Piet Hein Jongbloet's conception origin hypothesis is interesting, but we disagree that it ‘looks in the better position to explain reduced birthweight, intrauterine growth retardation and adverse outcomes in later life’.1 His assertion is based on animal studies that may not be relevant to humans and limited evidence from human studies that do not directly test the hypothesis.2 Jongbloet seems to have misunderstood our hypothesis that ambient temperatures at different points in pregnancy explain the seasonal patterning of birthweight.3 We do not assert that it is important in linking low birthweight to later disease outcomes. We found that the seasonal patterning of ......