Is keratin hair smoothing safe during pregnancy?

What does the evidence say about keratin hair smoothing during pregnancy?

1. Some hair straightening products release formaldehyde into the air when heated, and studies have suggested an increased chance for miscarriage among women who work around formaldehyde. 1
2. When the smoothing solution is heated, formaldehyde is released into the air as a gas, and in a poorly ventilated salon both the stylist and the client are at risk of inhaling it. Above 0.1 ppm it can cause watery eyes, burning in the eyes, nose, and throat, coughing, wheezing, and nausea. 2
3. FDA advises never applying these products at home and going to a licensed professional who uses gloves, eye protection, and proper ventilation, noting that longer and more concentrated exposure raises the potential health risks. 3
4. An exposure study of four professional smoothing products measured airborne formaldehyde of 0.08 to 3.47 ppm during blow drying, and found that even products labeled formaldehyde-free can reach or exceed occupational exposure limits. 4
5. US law does not require cosmetic products or ingredients, other than color additives, to have FDA approval before they go on the market, so no agency has reviewed a smoothing formula for pregnancy before it reaches the salon chair. 5

Is keratin hair smoothing safe in each trimester?

• First trimester. The window providers guard most closely. The exposure here is inhaled rather than absorbed, and a smoothing service can run an hour or more in the same room as the fumes.
• Second trimester. Postponing is still the standard advice. If your hair was already smoothed before you conceived, growing it out is not an exposure. Only reapplying is.
• Third trimester. No change. A heightened sense of smell and lingering nausea also make an hour in formaldehyde fumes genuinely unpleasant for a lot of people.