Washington: Daylight savings time - setting clocks an hour back or ahead according to seasons - may increase the risk of miscarriages in women undergoing IVF, according to a new study that shows the impact of circadian
rhythm changes on reproduction.
Daylight Saving Time is used to save energy and minimise the use of artificial light. It was first used in 1908 in Canada. Researchers at Boston Medical Centre (BMC) in the US and IVF New England said daylight savings time represents a subtle but widespread disruption to daily circadian rhythms. The one-hour difference has been previously reported to cause negative health impacts, such as increased instances of heart attacks, but little is known regarding its impact on
fertility.
"To our knowledge, there are no other studies looking at the effects of daylight savings time and fertility outcomes," said Constance Liu, who conducted the research at BMC. "We knew that we were researching an uncharted field, and
it was important for us to understand the effect a one-hour change had on patients undergoing in vitro fertilisation (IVF)," said Liu, who is now at Massachusetts General Hospital in the US.
Researchers looked at the pregnancy and miscarriage rates among a sample of patients undergoing IVF prior to and during daylight savings time, in both the fall and spring. The patients were then categorised into three groups based on the timing of their embryo transfer during daylight savings time. An embryo transfer refers to a step in the IVF process in which an embryo is placed into the uterus of a female with the intent of establishing a pregnancy.
The study found that miscarriage rates in IVF patients who had had a prior miscarriage were significantly higher among women whose embryo transfers occurred 21 days after spring DST began, compared to patients whose embryo transfers occurred before or well outside the spring DST window. Successful pregnancy rates did not differ between seasons or among the three groups or among the three groups during the change to standard time in the fall.
"While our findings on the impact of DST on pregnancy loss among IVF pregnancies are intriguing, they need to be replicated in larger IVF cohorts in different parts of the world that observe DST," said Wendy Kuohung from BMC.
The study was published in the journal Chronobiology International.
