How can you get advice on which drugs are safe in pregnancy?

While we don't know the risk that many drugs pose to a fetus, that doesn't mean that pregnant women have to fly completely blind. A teratogen is a substance that derails fetal development. Teratology information services have made it their mission to keep track of whatever information is available on the fetal safety of a wide range of drugs and other substances. Many of these services produce online factsheets as well as running telephone helplines. Women, and their doctors, can call these experts to learn more about the safety of a particular drug and receive individualised risk assessments.

We spoke to Laura Yates, Head of Teratology at the UK Teratology Information Service (UKTIS). Like many such services, UKTIS both provides information to the public and conducts research, tracking the cases of women who have taken medication, or been exposed to other potentially dangerous substances, during pregnancy.

The concept of having a teratology information service really came about after the thalidomide tragedy. The people that started it were predominantly scientists in the UK who were working on exposing animals to teratogens. What used to happen is that a lot of the doctors from the poison centre used to phone them up and say, "We've got this lady, this is what has happened, have you got any information that you could maybe share from what you've learned from animals?" And they came up with this concept of wanting to record details of the woman that the doctors phoned about and then following them up to see what happened to the baby after the pregnancy. And that's because in those days there were no studies at all on pregnant women. That model became a really important way of collecting data on new medicines. And the service has really grown from that.

The way we operate our teratology information service is slightly different. We only deal with healthcare professionals because we feel that it's not up to us to be telling a woman to start and stop her medicine. Really that decision has to be taken after careful consideration, and we also feel that some of the decisions are very complex. So we would encourage women on our website to go to their GP to have that discussion, and then that doctor contacts our service and has a discussion about the case. We also hold written information summaries on our website. Healthcare professionals can go there first and see if there's a review that answers their question, but if it's more complex they then call our national advisory service.

Completely variable. Sometimes it's undocumented ­– there's absolutely no human data. Sometimes the only human data is the outcome of cases we've actually recorded ourselves over 30 years. I can think of a few chemicals where there's just one or two animal studies, but we've had women who've been accidentally exposed or poisoned and then we've followed up the outcomes on those. But then if you look at something like the antidepressants or the SSRIs [selective serotonin reuptake inhibitors], those are really commonly used. And, as you're probably aware, about half of pregnancies are unplanned, so women becoming pregnant when they're taking an antidepressant is not uncommon. So there are loads and loads of studies that have looked at very big groups of women and looked at the effects on babies. So there's this complete range.

Antidepressants, I think, consistently. We get a lot of inquiries of antibiotics. We get queries about antipsychotics. The perinatal psychiatrists call a lot. We get doctors phoning quite a lot just saying, "Hi, I've got your monograph from 2012. Is there anything new that I need to know about?" And then we'll actively do a search.

That's quite a new initiative. We started increasingly getting calls from women saying, "I've taken this, and I really want to report it." Because we had historically only interacted with healthcare professionals, we weren't really in a position to take that information, and we were concerned about mixing the two data sources.

We started our own set of patient information leaflets – the information there is consistent with what's in our scientific documents. And that's been hugely successful. We just hit 1 million hits on the website this month.

The other bit is basically a self-reporting tool for women to use. So what we've done is we've created this kind of online maternity health record so women who want to can tell us about medicines. What we have tried to emphasise is that you don't have be taking a medication: we also need all those women with chronic illnesses who decide to stop taking medication, because they're a very important comparison group. But anyone who feels that they would like to contribute to what we know about medicines and pregnancy can start their own record, and then we are following up the babies. We're really keen to see what bumps comes back with. The reporting tool was only launched in April this year, and we've had a number of women creating reports so far.

Probably the most important message is to go and see your doctor before you're even thinking about trying for a baby. Quite often there are drugs that you would want to say, "You know, let's try to swap you to something else" or "Can we stop this drug?" And pregnancy is not the best time to be doing that. Or if a woman is not going to stop the drug, at least she knows what the risks are and can decide whether they're risks she's prepared to take and the necessary surveillance can be put in place.

So if, for instance, the medication causes birth defects, she could be booked in for a more detailed scan. It's really about planning pregnancies or, if a woman finds that she's inadvertently pregnant, seeking advice as soon as possible. And also just knowing that teratology information services exist. Despite the fact that all these services have been around for a long time, we still get comments saying, "Oh my goodness, I wish I had known about you sooner." There's no charge for the information. It's all free advice. So I think it's just about making women aware that these services do exist. That there is that support system in place. One of the big things we offer is often reassurance. Quite often, a woman's perception of risk is much worse than it actually is.

This interview has been edited for length and clarity.

This article first appeared on Mosaic and is republished here under a Creative Commons licence.