Fertile findings from pregnancy and shiftwork study

A shiftwork-dominated lifestyle ruled by the clock could significantly affect fertility, new research has revealed.

By jetlagging pregnant mice, Northwestern University scientist Fred Turek and his team found that, compared with controls, rodents subjected to regular shifts in their sleep-wake cycle, simulating a human doing bouts of nightwork, suffered a 40% birth-rate drop.

The work, published this week in PLoS One, also compared moving the body clocks of the mice backwards as well as forwards, finding that advancing the clock (leaving the animals short of sleep) had roughly twice the pregnancy impact of retarding the clock.

The researchers also highlight recent findings that the pregnant uterus as well as foetal tissues sync up their own internal chemical clocks with the body's main master clock, the suprechiasmatic nucleus based in the brain.

 Disturbance to the circadian rhythm, they speculate, is therefore likely to also impact on the biochemistry of the uterus and foetus, increasing the risk of adverse outcomes. This, they say, warrants closer scrutiny in human subjects, particularly since there are now reports of individuals struggling to fall pregnant when subject to work patterns requiring regular reorganisation of the body clock.