Collagen peptides are not proven unsafe during pregnancy, but they also haven’t been studied enough to be confirmed safe. WebMD’s clinical summary puts it plainly: “There isn’t enough reliable information to know if collagen peptides are safe to use when pregnant or breast-feeding.” That doesn’t mean collagen is dangerous. It means no one has run the rigorous trials needed to give a definitive answer, which puts it in the same category as many supplements during pregnancy.
What we do know is that the amino acids found in collagen, particularly glycine and proline, play important roles in fetal development. The question is whether getting those amino acids from a supplement powder is meaningfully different from getting them through food, and whether the supplement itself introduces any risks.
Why Your Body Needs More Glycine During Pregnancy
Glycine is one of the most abundant amino acids in collagen, and demand for it rises steadily as pregnancy progresses. It supplies the methyl groups needed to build fetal DNA and supports the cell division behind both maternal and fetal tissue growth. By late pregnancy, glycine becomes especially critical: it makes up roughly 25% of the amino acids in cartilage, and most fetal cartilage is synthesized during the third trimester.
Research published in the British Journal of Nutrition found that pregnant adult women can generally ramp up their own glycine production to meet this increased demand. Pregnant adolescent girls, however, could not maintain adequate glycine synthesis in late pregnancy, potentially leaving their fetuses vulnerable to impaired cartilage development and reduced linear growth. This suggests that for some pregnant people, dietary glycine intake matters more than others, and collagen-rich foods (bone broth, slow-cooked meats, chicken skin) are among the best natural sources.
Collagen and Pregnancy-Related Joint Pain
During the first trimester, levels of a hormone called relaxin begin to rise. Relaxin loosens spinal and pelvic ligaments to prepare for delivery, but it also increases joint laxity throughout the body and can trigger lower back and pelvic pain. This is one reason collagen supplements appeal to pregnant women in the first place.
There is some biological basis for the idea. Collagen peptides stimulate the cells responsible for maintaining connective tissue, enhance the structural matrix around joints, and have mild anti-inflammatory effects. A 2025 review in Our Dermatology Online concluded that collagen supplementation “may help alleviate lower back pain associated with pregnancy by improving joint stability and soft tissue resilience.” The language is cautious for good reason: this is based on the known biochemistry of collagen peptides and general population studies, not trials specifically conducted on pregnant women.
It Won’t Necessarily Prevent Stretch Marks
Many collagen products are marketed with skin benefits in mind, and preventing stretch marks is a common hope during pregnancy. The evidence here is thin. While oral collagen has been shown to improve skin hydration and elasticity in the general population, no study has directly confirmed that it prevents pregnancy stretch marks. An evidence-based review published in Archiv EuroMedica in 2025 concluded that “no topical or oral agent can yet be considered definitively effective for preventing stretch marks.” If you’re taking collagen specifically for this reason, temper your expectations.
The Real Risks: Contaminants and Hidden Ingredients
The collagen peptides themselves, being simple chains of amino acids, are unlikely to be harmful. The bigger concern is what else comes in the container. Supplements in the United States are not reviewed by the FDA before they reach store shelves, which means quality varies enormously between brands.
Heavy Metals
Collagen is derived from animal bones, skin, and connective tissue, all of which can accumulate heavy metals. Independent testing of collagen products has detected measurable levels of lead, cadmium, arsenic, and mercury. In one tested product, lead levels were below 0.01 parts per million and mercury was below 0.02 ppm, both very low. But not every brand tests this thoroughly, and during pregnancy even small, chronic exposures to lead or mercury carry outsized risks for fetal brain development. Without a certificate of analysis from the specific product you’re considering, you’re guessing.
Added Ingredients
Many collagen powders are not pure collagen. Blends frequently include herbs, adaptogens, high-dose vitamins (particularly vitamin A, which is harmful in excess during pregnancy), or botanical extracts that have not been evaluated for safety in pregnancy. A product labeled “collagen” might contain a dozen other ingredients. Always read the full ingredient list, not just the front label.
How to Choose a Safer Product
If you decide to use collagen peptides during pregnancy, quality control is the single most important factor. Look for products that carry a third-party certification, such as NSF Certified for Sport or USP Verified, which verify that the product contains what the label says and has been screened for contaminants. These certifications are not common on collagen products, but they do exist.
Beyond certification, a few practical guidelines help reduce risk:
- Source matters. Collagen from grass-fed cows or wild-caught fish tends to have fewer additives and lower contaminant exposure than products from conventional animal sources. If you have a beef or fish allergy, avoid collagen sourced from that animal entirely.
- Simpler is better. Choose a product with one ingredient: hydrolyzed collagen peptides. Skip blends with added herbs, sweeteners, or vitamins unless you’ve verified each ingredient is pregnancy-safe.
- Request a certificate of analysis. Reputable brands will provide third-party lab results showing heavy metal levels for the specific batch you’re purchasing. If a company won’t share this, that tells you something.
Food Sources as an Alternative
The amino acids in collagen supplements are not unique to supplements. Bone broth, chicken with skin, pork skin, sardines, and slow-cooked tough cuts of meat all provide glycine, proline, and hydroxyproline in forms your body readily absorbs. Vitamin C is needed to build collagen from these amino acids, so pairing collagen-rich foods with fruits and vegetables supports the process naturally.
For women who are uncomfortable with the uncertainty around supplements, food-based sources offer the same building blocks without the risks of contaminants or unregulated additives. This is the conservative approach, and during pregnancy, conservative tends to be reasonable.