When you’re pregnant and need to take a medication-whether it’s for depression, epilepsy, or an autoimmune condition-you’re caught between two urgent needs: staying healthy yourself and protecting your baby. But here’s the hard truth: pregnancy registries are the only real system we have to answer that question safely. Most drugs used during pregnancy haven’t been tested in pregnant women during clinical trials. Ethical rules keep them out. So what do we know? Not much-unless a registry is tracking it.

Why Pregnancy Registries Exist

Pregnancy registries weren’t created by accident. They’re the direct result of tragedy. After thalidomide caused thousands of severe birth defects in the 1960s, the medical world realized we couldn’t wait until harm was done to understand drug risks. Today, these registries are a formal part of drug approval in the U.S. and Europe. The FDA and EMA require them for certain medications-especially biologics and psychiatric drugs-that are likely to be used by women who could become pregnant.

These aren’t passive databases. They’re active studies. Women are enrolled as soon as they start taking a medication during pregnancy. Researchers collect detailed info: exactly which drug, what dose, when it was taken, other meds, smoking, alcohol, even pre-existing health conditions. Then they follow the pregnancy-tracking miscarriages, preterm births, low birth weight-and most importantly, whether the baby has major birth defects.

What These Registries Actually Tell Us

The goal isn’t to prove a drug is 100% safe. That’s impossible. The goal is to rule out serious risks. For example, if a drug is linked to a rare pattern of facial or heart defects seen in 5 out of 100 exposed babies, that’s a red flag. Registries caught that with lamotrigine and valproate years ago. Now doctors know to avoid valproate in pregnancy entirely.

But here’s what they don’t do well: detect small increases in risk. If a drug raises the chance of a cleft palate from 1 in 1,000 to 2 in 1,000, you’d need over 1,200 exposed pregnancies just to spot it with confidence. Most registries enroll fewer than 500 women. That’s why some drugs still have vague labels like “use only if benefit outweighs risk”-because the data just isn’t there yet.

Psychiatric medications are a big focus. The National Pregnancy Registry for Psychiatric Medications, run by Massachusetts General Hospital, has tracked over 3,000 pregnancies since 2007. It found that SSRIs like sertraline don’t cause major structural birth defects at higher rates than the general population. That’s huge. It gives doctors and patients real reassurance. But it doesn’t tell us about long-term brain development-so now they’re following kids until age 12.

How They Compare to Other Methods

You might wonder: why not just look at insurance claims or electronic health records? Those databases are huge-they can include hundreds of thousands of pregnancies. But they’re messy. Did the woman actually take the drug? Was it prescribed for depression or migraines? Was the baby’s defect recorded accurately? Often, no.

Registries beat them on data quality. They ask the mother directly. They verify prescriptions. They track exposure before the outcome is known. That cuts out recall bias-the kind where a mom whose baby has a defect remembers taking a pill, but a mom with a healthy baby forgets she took the same one.

But registries lose on scale. They’re slow. They cost between $500,000 and $2 million a year to run. And they rely on volunteers. Only 15-20% of eligible women enroll. Many are scared, overwhelmed, or don’t trust the system. Some think they’ll get instant answers-and then get frustrated when the registry says, “We’re still collecting data.”

Who’s Running Them and How They Grow

In the U.S., there are over 80 active pregnancy registries. About 30 new ones start every year. Most are run by pharmaceutical companies as a condition of FDA approval. But they’re not alone. Hospitals, universities, and nonprofits like MotherToBaby partner with them to recruit women and provide support.

The biggest registries focus on drugs for conditions that affect women of childbearing age: depression, anxiety, bipolar disorder, epilepsy, rheumatoid arthritis, and psoriasis. Biologics-those expensive injectable drugs for autoimmune diseases-are now the fastest-growing category. Since 2018, two-thirds of new biologics came with a registry requirement.

The FDA launched the Pregnancy Safety Research Network in 2022 to link these scattered efforts. They’re trying to standardize how data is collected, so findings from one registry can be combined with another. That’s critical. If three registries each track 400 women on different antidepressants, pooling them gives you 1,200 data points-enough to spot subtle signals.

The Real Human Side

Behind every registry number is a woman making a terrifying choice. A woman with severe depression who knows untreated illness can harm her baby too. A woman with lupus who needs her medication to stay alive. She wants to know: “Will my child be okay?”

Registries can’t give her a yes or no. But they can give her something better: context. When a woman joins a registry, she often gets personalized updates. She learns that 87 out of 100 women on her medication had healthy babies. That’s not proof of safety-but it’s not fear-mongering either. It’s honest, real data.

One mother in the psychiatric registry told researchers: “I didn’t want to be a guinea pig. But I wanted my child to have a chance. If my data helps the next woman, then it matters.” That’s why 78% of participants say they’re glad they joined-even if they never got a clear answer.

The Limits and the Future

No registry can prove a drug is completely safe. They can only say: “We haven’t seen a dangerous pattern yet.” That’s not enough for some. Experts like Dr. Sonia Hernandez-Diaz argue we need a tiered system: use registries to spot red flags, then use big data to measure the actual risk.

That’s already starting. Researchers are now linking registry data with state birth defect registries, hospital records, and even newborn screening results. Imagine a system where your prescription triggers an automatic registry enrollment-and your baby’s health data flows in quietly, without extra phone calls or forms. That’s the goal.

Meanwhile, the number of drugs with pregnancy data is growing. In January 2024, the National Pregnancy Registry for Psychiatric Medications added 18 new medications, bringing its total to 45. That’s more than double what was available a decade ago.

But the system still depends on women stepping forward. It depends on doctors asking. It depends on companies funding it. And it depends on us accepting that safety isn’t black and white-it’s a slow, messy, human process of gathering evidence, one pregnancy at a time.

What You Can Do

If you’re pregnant and taking any medication-prescription, over-the-counter, or supplement-ask your provider: “Is there a pregnancy registry for this?” If there is, consider joining. It takes 15 minutes to enroll. You’ll get regular updates. You’ll help future moms. And you’ll be part of something bigger than yourself.

If you’re not pregnant but planning to be, talk to your doctor now. Find out what drugs you’re on and whether they’re tracked. Knowledge isn’t just power-it’s protection.