“We typically have more babies born in July, August and September,” says Mary Lou Kopas, chief of midwifery at University of Washington Medical Center - Northwest. “Count back nine months and, well, we’re looking at November to January.”
The evidence isn’t purely anecdotal, either. According to the National Center for Health Statistics, more babies are born in northern states like Washington around June and July, while southern states experience a peak a bit later in October and November. That means prime conception time in the United States occurs in fall and winter.
Is it the cozy sweater weather that’s causing us to turn up the heat? Do our longer nights have something to do with it? Or is it something biological that we just can’t explain?
Kopas shares her thoughts on the matter as well as some helpful facts for what to know if you hope to get pregnant this winter.
Why more babies are conceived in fall and winter
Close your eyes for a moment and picture Bambi. In your imagination that little white-tailed fawn is probably frolicking in a grassy meadow studded with wildflowers — and there’s a reason for that.
In the animal kingdom, many newborns emerge right around springtime, when food sources are plentiful again and the likelihood of survival is much higher. To get this timing right, certain species have evolved to the point where females only go into estrus (aka heat) during specific seasons.
The same could be true of humans, Kopas says, but there’s not enough solid evidence to say one way or another.
Social aspects like spending more time in bed when it’s cold and dark may play a part, she speculates, while biological factors similar to what goes on in the animal world could also factor into conception trends.
“Obviously, humans menstruate once a month, and we know that people conceive all times of the year, but there could be a biological factor that makes us more fertile at certain times,” she explains. “The thing about humans, though, is that while we’re mammals, we have evolved to the point where we can control our environment, and sociological factors are much bigger for us.”
What to know about getting pregnant in winter
Whether your conception revolves around evolutionary impulses, social factors or something completely spontaneous — like a gorgeous guest at a holiday party — there are a few things to keep in mind if you get pregnant or plan to start trying during cold-weather months.
“When you’re planning pregnancy, we encourage you to see your doctor or midwife for a pre-conception visit so we can review your health history, any medications you’re taking and, ideally, help you be in the best position for a healthy start to pregnancy,” Kopas says.
Even if you don’t make it in for a pre-conception checkup, Kopas recommends all women of child-bearing age stay topped up on folic acid to prevent neural tube defects. Half of pregnancies are unplanned, she says, so it’s crucial to get folic acid from a prenatal vitamin or a balanced diet whether or not you’re trying to conceive.
During these dreary winter days, it’s also important to mind your vitamin D levels, something that’s particularly tough in the Pacific Northwest. You should get at least 2,000 IUs per day, either from a supplement or foods you eat.
“We also strongly recommend that all pregnant women get their flu shot,” Kopas adds. “Pregnancy is a risk factor for getting a severe case of the flu, and the antibodies you make from the flu shot will also pass on to your baby via the placenta and give that infant some protection after they’re born.”
These extra antibodies are especially important because babies can’t get vaccinated until they’re six months old and rely on passive immunity — antibodies that they get from you in utero and through breastmilk — as newborns.
How to approach birth control year-round
Not exactly ready to have a newborn next summer? Sex happens, so make sure you’re prepared.
You’re most fertile midway through your cycle, Kopas says, around two weeks before you expect your period. For those who use natural family planning, this is the time to avoid sex.
If you use birth control, think about what options will work well in any situation.
“We live in the age of reversible contraception,” Kopas notes. “Intrauterine devices (IUDs) are more effective and have fewer side effects and don’t affect your future fertility. We have shots and skin implants and a lot of other long-acting reversible contraception that many people aren’t aware of.”
If you’re not on regular birth control — a daily pill, patch, ring, IUD or skin implant — you might consider keeping condoms in your purse so you always have one on hand.
So whether you’re hoping to join those baby birth trends next year or are plenty happy the way things are now, take care this winter and have fun making merry.