I have been down more rabbit holes researching this post than Alice (in Wonderland). I started out by thinking that it would be useful to put together a list of cosmetic ingredients that should be avoided by pregnant women. I didn’t assume that this would be easy, but I didn’t anticipate that there would be so much contradictory information and so many unsubstantiated claims. It turns out that differentiating between what’s safe, or not to use when pregnant is not always clear cut.

My starting point was Truth In Aging itself and our interview with Dr Jason P Rubin. He gave us a list of ingredients for pregnant women to avoid and links to relevant scientific studies. However, when I looked into the studies for this post, I found that they were largely animal studies on oral consumption. Doing more research, I found that either there are no studies of topical use, or that medical experts deemed these ingredients safe. So here are some of the ingredients that pregnant women are sometimes told to avoid and what I have been able to find out about them.

There are a couple specifically that experts say are safe:

Aloe vera. Although there is some concern about oral consumption of aloe as it is linked to increased frequencies of embryonic death and skeletal anomalies in animal studies, the Mayo Clinic says that topical use is safe.

Salicylic acid. Abeta-hydroxy acid found in many acne products that is mentioned in the Rubin interview where he cites animal linking it to higher rates of fetal malformation and fetal death in animal studies. However, the Illinois state health authority says that the risks of aspirin late in pregnancy are "probably not relevant" for a topical exposure to salicylic acid, even late in the pregnancy, because of its low systemic levels. There are no studies specifically looking at topical salicylic acid in pregnancy.

There are, however, some ingredients that most experts agree should be avoided by pregnant women:

Tretinoin (Retin A). There are case reports linking tretinoin to infant malformations. On the other hand, there are two studies that failed to find an association. The Ilinois Health Authority concludes: “While such risks are likely to be low given the low topical absorption, health professionals should encourage women to weigh the risk and benefits of tretinoin during pregnancy”.

Retinoids Isotretinoin (Accutane, Roaccutane) A known teratogen that is contraindicated during pregnancy due to the fetal malformations it causes. It is recommended that isotretinoin be discontinued at least one month prior to attempting pregnancy.

Oxybenzone. A chemical sunscreen ingredient. Mothers with high levels of oxybenzone in their bodies were more likely to give birth to underweight baby girls (Wolff 2008). The CDC recommends that small children avoid products that contain it.

Phthalates. As recently as 2010, A new study has found that exposure to phthalates, chemicals used in perfumes, nail varnish and plastics, at the prenatal stage can affect development and behavior in children.

There are some that are a little more border line and expectant mothers will want to make up their own minds based on the available information and the advice of their doctors. These include:

Glycolic acid. A chemical exfoliant commonly found in facial peels, has been found to be a developmental toxin in animal studies. However, this was oral and dose dependent. I haven’t been able to find any research on topical use of glycolic and pregnancy. The general consensus seems to be that it is safe, except that some pregnant women are more sensitive to sunburn and all AHAs will exacerbate that.

Benzoyl peroxide. A topical treatment for acne that has antibacterial effects. There are no any animal or human reproductive studies on topical benzoyl peroxide. However, there are no case reports about benzoyl peroxide and birth defects. About 5% of each topical dose is absorbed systemically. Consequently, it is regarded as low risk.

Estrogenic chemicals. This is a controversial area as the science is contradictory. Some studies suggest that estrogenic chemicals should be avoided while the reproductive system is still maturing, which includes newborns, children, and prepubescent teens. However, if you look specifically at parabens (which are estrogenic), it is not clear cut. A 2009 study on mice concluded: “in vivo estrogenicity of parabens may not be as potent as previously reported”. The CDC says: “At levels producing maternal toxicity, parabens were not teratogenic in animal studies (Daston, 2004; Elder, 1984, Moriyama et al., 1975). Butyl paraben may alter male reproductive organ size and sperm numbers and activity, but animal studies have been inconsistent.”

We’ll keep refining and updating this information. In the meantime, if anyone knows of research that we should include or wants to know about any additional ingredients and safety during pregnancy, let us know.