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Wife’s night shifts may be factor in ability to conceive

Fri., Aug. 2, 2013

Dear Mr. Dad: My wife and I have been trying to have a baby for the past year. Both of us have been thoroughly checked out and neither of us has any physical conditions that could be causing problems. The doctor says it’s “unexplained infertility,” which isn’t helpful at all. My wife usually works late afternoons or night shifts (she’s a nurse) and is always tired. Could that be contributing to our difficulty conceiving?

A. “Unexplained infertility” has to be one of the most frustrating things a couple can hear. All it means is that even after spending thousands on diagnoses and fertility treatments, you’re not any closer to having a baby than you were before. But in your case, your wife’s work schedule may provide a clue.

A recent study done by researchers in England found that women who work any shift other than a traditional 9-5 are twice as likely to be what’s called “sub-fertile,” a fancy way of saying that they haven’t been able to get pregnant for a year or more. And women who work night shifts are 80 percent more likely than day-shift women to have problems conceiving. In addition, working odd hours can disrupt a woman’s menstrual cycles and increases the risk of miscarriage by nearly 30 percent.

Why shift work is such a fertility killer isn’t completely clear. We know that sleep deprivation can throw off your body’s internal clock, and that can lead to increased levels of stress hormones and blood pressure. It’s also possible that people who work night shifts are more likely than others to get less exercise and to eat unhealthy food (several studies have found that sleep-deprived people make poorer food choices than those with more regular sleep patterns).

If that isn’t enough to get your wife to put in a request for a day shift, there are two more interesting pieces of sleep-related information that might help. First, sleep deprivation has already been linked with a number of conditions that may interfere with fertility, including obesity, diabetes, and reduced immune system functioning. There’s also a proven connection between long-term night shift work and an increase in breast cancer risk – particularly among nurses (a recent Canadian study just found the same connection for all night-shift working women, not just nurses). The World Health Organization says that the late-night shifts interfere with the production of melatonin, a hormone that may prevent tumors from growing. Melatonin is generally produced by the body at night. But having the lights on during night shifts throws off production. Other scientists suggest that since night-shift workers typically have less exposure to natural sunlight (in part because they’re sleeping during the day), vitamin D production decreases to a point where disease risk increases.

The second piece of news is more cosmetic, but I’m sure your wife will be interested. A recent study from University Hospitals Case Medical Center in Cleveland found that sleep-deprived women show signs of premature aging, including fine lines, reduced skin elasticity, slackening of the skin, and uneven pigmentation, according to Dr. Elma Baron, the study’s lead researcher. Poor-sleeping women also have a harder time recovering from sun exposure.

While this doesn’t completely explain away your unexplained infertility, it may give you and your fertility doc something to discuss. At the same time, have your wife bring this up with her supervisor at work. Nursing shifts are often assigned by seniority, with less-senior people getting the worst ones. If she can’t change her work schedule, it’ll be up to you to help her get more sleep at home.

Read Armin’s blog at, send email to, and follow him on Twitter @mrdad.


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