For years we’ve had worries that taking an antidepressant during pregnancy could spell big problems. In fact, in 2006, the FDA issued a warning cautioning doctors to be careful when prescribing these medications to women who became pregnant — even if the woman’s symptoms had improved greatly while on the drug.

The concern was over a problem called pulmonary hypertension. Basically that’s a life-threatening condition involving the circulation of the lungs. And if it happens in a baby, it can be very difficult to treat.

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Although rare, it seemed to develop more frequently in babies whose mothers were on antidepressant therapy during pregnancy as the lungs were entering their final stages of development.

So the FDA said: after the 20-week mark of pregnancy, think about holding off on antidepressants, particularly those known as SSRIs, or Selective Serotonin Reuptake Inhibitors. Common SSRIs include the drugs Prozac, Paxil, Zoloft, Lexapro, Celexa and Paxil.

Now comes a new 10-year study in JAMA which followed about 4 million pregnant women, of which about 102,000 used an SSRI after 20 weeks.

The results were reassuring. Compared to women who did not take an antidepressant during pregnancy, those who did had less than a one-third of 1 percent rate of having babies with pulmonary hypertension . That’s a miniscule difference. And remember, once again, the rate of pulmonary hypertension is rare to begin with — typically about two babies out of every 1,000 in all pregnancies.

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So what’s a mother-to-be to do if she is on an antidepressant and doing well? That’s a question that does not have an answer that includes everyone. The decision of the risks versus the benefits needs to be made on a personal basis.

So on the one hand, pulmonary hypertension can be life-threatening.

On the other, a mom’s risks of problems can increase if she goes off her medication. If depression becomes uncontrolled, there’s a concern about problems with mood, sleep, proper nutrition, tobacco-avoidance, etc. Plus the rate of post-partum depression goes up as well.

Tough problems mean tough decisions, but this study does offer more guidance — and relief.

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Dr. Dave Hnida is CBS4’s Medical Editor. He blogs about the latest studies and trends in the health world. Read his latest blog entries, check out his bio or follow him on Twitter @drdavehnida