Taking Charge of Your Fertility

Researchers have found lifestyle-related factors may delay or prevent pregnancy — find out what you can do to make conception more likely.

If you are longing for a baby but having difficulty getting pregnant, you aren’t alone. Around six percent of married American women of childbearing age have difficulty achieving pregnancy, according to the Centers for Disease Control and Prevention (CDC). If you are younger than 35 and have tried for a year or more to get pregnant with no success, or if you are 35 or older and still aren’t expecting after six months of trying, CDC experts suggest both you and your partner talk to your doctor about possible fertility testing.

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Taking charge of your fertility

But if no reason for your difficulty in getting pregnant is identified, or if you simply want to raise the odds you’ll be expecting sooner than later, consider the new findings of two groups of researchers. They’ve identified lifestyle factors — the weight of both partners and the kind of work a potential mom-to-be does (and when she does it) — that can make pregnancy harder to achieve.

A National Institutes of Health (NIH) study concluded it takes far longer for a significantly overweight woman and her also overweight partner to achieve pregnancy than normal-weight couples.

"A lot of studies on fertility and body composition have focused on the female partner, but our findings underscore the importance of including both partners," said Rajeshwari Sundaram, PhD, an NIH researcher at the Eunice Kennedy Shriver National Institute of Child Health and Human Development. "Our results also indicate that fertility specialists may want to consider couples' body compositions when counseling patients."

Sundaram and colleagues followed 501 couples from Michigan and Texas from 2005 to 2009 who were aiming for a pregnancy. The women, who were between 18 and 44, all recorded their monthly menstrual cycles, intercourse, and results of pregnancy tests for a year or up until pregnancy was achieved.

The research team also made note of each research subject’s body mass index (BMI), a measure of body fat based on weight in relation to height. The couples who were significantly overweight were divided into two categories — obese I (a BMI from 30 to 34.9) and obese class II (a BMI of 35 or greater).

Then the scientists compared the average time it took for couples of normal weight to achieve pregnancy compared to those who were obese. It took the obese couples from 55 to 59 percent longer for a pregnancy.

The study concluded that fertility specialists should consider taking couples' weight into account when counseling them. By losing weight, parents-to-be may not only reduce the time needed to conceive a baby, but they can also gain multiple health benefits, such as lowering the risk of type 2 diabetes, heart disease, and several types of cancer, according to the NIH study team.

Another recent study from the Harvard T.H. Chan School of Public Health found an additional factor that can make conception difficult. Whether a woman works at night — and whether her job involves heavy lifting — can influence if pregnancy occurs.

The researchers studied almost 500 women seeking infertility treatment at Massachusetts General Hospital between 2004 and 2015. They looked at the women’s test results of fertility biomarkers, including levels of follicle-stimulating hormone (FSH), estrogen, and the number of mature eggs capable of developing into healthy embryos. Then they compared the levels of these biomarkers to the type of work the women performed.

The study didn’t find any link between occupational factors and estrogen or FSH levels. However, it did reveal a worrisome association between fertility problems and jobs that required women to move or lift heavy objects. Those women had fewer total eggs and fewer mature eggs, compared to women who never had to lift heavy objects at work.

The association was the strongest in women who were 38 or older, and in women who were overweight or obese. In addition, the women who worked night shifts also had fewer viable eggs that could result in pregnancy.

Just how moving or lifting heavy loads could damage egg quality remains a mystery, the researchers noted. However, they suspect working night shifts disrupts the normal circadian rhythm – the body’s internal, biological “clock” –affecting eggs.

"Our study suggests that women who are planning pregnancy should be cognizant of the potential negative impacts that non-day shift and heavy lifting could have on their reproductive health," said Harvard public health research fellow Lidia Mínguez-Alarcón, lead author of the study.

For more information about causes and treatments for infertility, visit the CDC’s Infertility FAQs page.

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