Science Says Birth Date Can Affect Baby’s Health

Pregnancy and the months after birth are absolutely vital in determining how a baby will grow and develop. In fact, those first few months of life can even impact a child’s long-term health, sometimes leading on into adulthood. Stress, exposure to harmful chemicals, pet dander, food source, interaction, physical contact, and so much more all play a part. But can the time of year your baby is born be a factor as well?

newborn baby

According to science, it most certainly can.

“The scientific literature goes back almost 100 years linking birth to almost anything under the sun, from income to life expectancy to height,” Hannes Schwandt, PhD, an economist at Princeton University’s Center for Health and Wellbeing.

For example, a 2013 study by Schwandt and his co-author, Janet Curie, PhD, found that mothers who get pregnant in May and are due in the winter have a 10% higher risk of delivering prematurely. Researchers speculate that the higher rates of influenza between January and February may play a part in this statistic since it’s known that catching the flu can actually trigger premature labor in women nearing full-term.

But that still doesn’t make May a bad month to conceive, Schwandt said.

“In some years, flu seasons peak much earlier,” he said. “In that case, women who conceived in earlier months would be at greater risk.”

Either way, receiving a flu shot is a mother’s best ally when it comes to protection for her and her baby during the winter months.

In contrast to the winter babies being at risk for premature birth, you have the autumn babies that, for some strange reason tend to have super powers . . . well, sort of.

According to a 2014 study published in the International Journal of Sports Medicine, kids with fall birthdays appeared to be more naturally fit than those born during other times of the year. And those born in November can run at least 10% faster, jump 12% higher, and are 15% more powerful than the same-aged child born in April.

One possible explanation is that mothers who are pregnant through the summer are exposed to more sunlight, thereby increasing their levels of vitamin D—an essential nutrient for healthy fetal development. So important, in fact, that the American Congress of Obstetricians and Gynecologists say that all women (pregnant or not) should get at least 600 international units of vitamin D per day.

Low levels of this nutrient could also explain why springtime babies are more likely to develop multiple sclerosis later in life. This was suggested by a 2013 Queen Mary University of London study that found that vitamin D levels in babies born in May were about 20% lower than those born in November. Those same babies also had twice as many autoreactive T-cells (potentially dangerous cells that could later turn against the body’s own immune system). And, while not cause-and-effect, other studies have found a correlation between low vitamin D levels and MS risk, and the risk is lowest for those born in November and highest for those born in May.

Though most pregnant women get enough of it through prenatal vitamins, those with darker skin or that are pregnant through the winter are most susceptible to low levels. Routine screening isn’t done, but mothers concerned about adequate levels can talk to their doctors.

However, Schwndt pointed out that few of the previous studies on birth season have looked at other factors that could affect a child’s health and development—factors like length of pregnancy or socioeconomic status. And, the reality is, timing of birth won’t have anywhere near the effect as other factors like healthy eating, the avoidance of cigarettes and alcohol, and regular exercise.

“Unless you have a personal preference, there is no ‘best or worst’ month to get pregnant or have a baby,” he said “Taking care of yourself and getting proper prenatal care will make a much bigger difference than whether you give birth in January versus June.”

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About the author


Kate Givans is a wife and a mother of five—four sons (one with autism) and a daughter. She’s an advocate for breastfeeding, women’s rights, against domestic violence, and equality for all. When not writing—be it creating her next romance novel or here on Growing Your Baby—Kate can be found discussing humanitarian issues, animal rights, eco-awareness, food, parenting, and her favorite books and shows on Twitter or Facebook. Laundry is the bane of her existence, but armed with a cup of coffee, she sometimes she gets it done.

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