Is Working Just as Bad as Smoking During Pregnancy?

Smoking during pregnancy and working during pregnancy. What do these two things have in common? According to a new study from researchers in Great Britain, punching in after the eighth month of pregnancy may be just as harmful to babies' healthy growth as lighting up.

The University of Essex research—which drew on birth data from the UK and US—found that moms who continued to work up until their due dates gave birth to babies an average of .5 pounds (230 grams) lighter than babies born to moms who stopped working between six and eight months, which put these babies at risk for low birth weight. Similar effects on birth weight can be seen in babies born to moms who smoke, says researchers.

Time to rethink those carefully laid maternity leave plans? It may depend on your line of work. Researchers didn't ask women to identify what they did for a living, but did ask about their education levels. Moms with babies most at risk for low birth weight were also moms with lower education levels. This could be a tip off that the types of jobs singled out in the study are those requiring more physical demands, such as standing for long periods. Age also mattered—birth weights of babies born to mothers under the age of 24 did not appear affected by work, but in older mothers the effect was more significant.

The reaction from the hard-working momosphere is mixed. "I only have six weeks of maternity leave. Following the logic of this study, I would use almost all of it up before my baby even gets here," says Kara Markham, a mom-to-be from Twin Falls, Idaho.

"Why don't we pass more laws to protect pregnant women from having to do so much demanding work right up until they're due? I am a kindergarten teacher and even that requires much more physical stamina that you may think!" says Amanda Mills from San Francisco, California.

But there are laws already on the books. According to the Pregnancy Discrimination Act, an amendment to the Civil Rights Act of 1964, if an employee is temporarily unable to perform her job because of her pregnancy, the employer must treat her the same as any other temporarily disabled employee. For example, if the employer allows temporarily disabled employees to modify tasks, perform alternative assignments, or take disability leave or leave without pay, the employer also must allow an employee who is temporarily disabled because of pregnancy to do the same.

In other words, talk to your doctor or midwife about your job and how it meshes with your pregnancy—and then talk to your employer.

How are you coping with the physical demands of your job? When does your maternity leave start?