Mothers-to-be who are anxious or depressed during pregnancy are more likely to have babies who have sleep problems by age 18 months.
"Anxiety and depression don't predict [a baby's] total sleep, but do predict sleep problems and disruptive sleep," says researcher Thomas O'Connor, PhD, associate professor of psychiatry at the University of Rochester Medical Center in New York. "The babies may sleep just as long, but they wake up more often and they have trouble falling asleep."
The study appears in the July issue of the journal Early Human Development.
O'Connor and his colleagues evaluated data from a large study in England called the Avon Longitudinal Study of Parents and Children (ALSPAC). Women who were to deliver their babies between 1991 and 1992 answered questions about their mood during pregnancy and the baby's sleep habits later.
The core sample included more than 14,000 pregnancies. For this study, O'Connor's team looked at the baby's sleep habits at ages 6 months, 18 months, and 30 months, looking at data at each time point from more than 10,000 to nearly 11,500 women.
They asked about a baby's total sleep time, the number of awakenings, and other sleep problems, such as difficulty going to sleep or nightmares.
Overall, the babies' total sleep time was about the same -- 12 hours daily, regardless of their mother's moods during pregnancy.
But mothers who were more anxious and depressed during their pregnancies reported more sleep problems in their babies at ages 18 months and 30 months, but not at 6 months. The increase in sleep problems was still there even after controlling for other factors that might play a role, such as their mood after childbirth.
The lack of an effect at age 6 months is understandable, O'Connor tells WebMD. At age 6 months, he says, "infants are still developing a sleep rhythm. You really can't talk about sleep problems at 6 months because that is the nature of the beast. By 18 months and certainly by 30 months, the children should have developed a sleep rhythm or pattern."
But those born to anxious or depressed mothers were less likely to develop that healthy sleep pattern, he found.
For instance, O'Connor tells WebMD, "Mothers with elevated anxiety at 18 weeks were 39% more likely to have children with sleep problems at 30 months. Mothers depressed at 32 weeks were about 40% more likely to have a child with sleep problems at 30 months. That's true even after controlling for smoking, alcohol intake, and postnatal mood."
His recent research, O'Connor says, follow others' research showing that mothers who report being stressed during pregnancy have children with higher rates of behavioral problems, as well as hyperactivity and anxiety.
What's Behind the Pregnancy Mood-Sleep Link?
O'Connor and his colleagues speculate that the stress hormone cortisol is behind the pregnancy mood and sleep problems link. "We know moms who are anxious in pregnancy have higher levels of the stress hormone cortisol," he says. "There is an association between a pregnant woman's level of stress hormone and stress hormone in the amniotic fluid. The placenta has an enzyme that breaks down the stress hormone. But evidently some still gets through.
"Moms who have higher levels of the stress hormone during pregnancy have babies exposed to higher levels of stress hormones," O'Connor says. And, that, he speculates, may influence the part of the brain that helps regulate the body's internal clock, including sleep habits.
The study makes sense, and will hopefully help dispel some pregnant women's notions that only external substances can adversely affect the pregnancy, says Diana Dell, MD, assistant professor of obstetrics and gynecology and psychiatry at Duke University Medical Center, Durham, N.C., who is both an ob-gyn and a psychiatrist.
"I've said to my patients, when the mother-to-be is anxious or depressed, you generate some noxious chemicals associated with that, and in terms of development it is not good," Dell says.
The new study adds to growing literature about infant sleep problems, says Judith Owens, MD, a sleep expert for the American Academy of Pediatrics and an associate professor of pediatrics at the Warren Alpert School of Medicine at Brown University, Providence, R.I. But she notes that the link between the mood of a woman during and after pregnancy and her baby's sleep is a complicated one.
"We know infant sleep is related to maternal depression [after childbirth]," she says. On the other hand, "If a mother has an infant who is not sleeping well, she is more likely to be anxious and depressed."
What to Do?
The new findings shouldn't make mothers-to-be who are anxious or depressed feel guilty, says Dell. "Women are under enormous pressure to make perfect babies and to be perfect moms."
If a woman feels more than a little anxious or depressed during pregnancy, seeking help as soon as possible is wise, Dell and Owens agree. "Moms need to be well during pregnancy."
Treatment might include psychotherapy or medication. "The current cultural bias is against [antidepressant] medication use [during pregnancy]," Dell says. But treatment should be decided case by case.
"If a mom has a mild depression, psychotherapy [talk therapy] may make her well," Dell says. "But if it's severe, psychotherapy may not be enough." For some women, she says, taking the medication for depression may carry less risk than not taking the medication and suffering the effects of the depression.
Some women's depression and anxiety may decline if they also ask for social support, Owens says. "Don't just ask for professional help," she tells pregnant women who are anxious or depressed. Asking for social support -- such as housecleaning help -- can also improve the situation, she says, especially if the newborn is not the mother's first child.
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