How moles change in pregnancy, what studies show about melanoma outcomes, and how biopsy, surgery, and future pregnancy plans are handled.
Melanoma is among the cancers most often diagnosed during pregnancy. The main reason is age: melanoma is one of the more common cancers in women in their 20s and 30s. The American Academy of Dermatology (AAD) states that pregnancy itself does not appear to raise the risk of getting melanoma. Doctors use the term pregnancy-associated melanoma for a melanoma found during pregnancy or within 1 year after delivery.
Skin darkens in many places during pregnancy. The line down the abdomen, the nipples, and patches on the face can all deepen in color. Moles take part in this to a small degree. According to DermNet, more than 10% of pregnant women notice a mole getting darker or larger.
Location explains most of the growth. Moles on the abdomen and breasts widen as the skin stretches, and they do so evenly, keeping their shape. Moles on the back, arms, and legs show no significant change in size. Under a dermatoscope, a handheld lighted magnifier, pregnancy moles show subtle changes that dermatologists recognize as harmless.
Other changes call for an exam, pregnant or not:
A skin biopsy removes a small piece of skin under local anesthesia. The AAD states that testing for melanoma is safe during pregnancy and that the local anesthetic is safe as well. Lidocaine, the usual choice, has a long record of use in pregnant patients, and the small amounts injected into skin stay mostly at the site.
DermNet's guidance is direct on timing. Minor skin surgery under local anesthetic can be done safely at any stage of pregnancy, and it should not be put off until after delivery when melanoma is suspected. Waiting several months gives a melanoma time to grow deeper, and depth is the strongest predictor of outcome.
Older reports from the mid-1900s suggested that melanoma behaved more aggressively in pregnant women. Newer and better-controlled studies, which compare women with tumors of the same thickness and stage, have mostly not confirmed this.
A Mayo Clinic study (Davidson and colleagues, Melanoma Research, 2024) compared 83 women with pregnancy-associated melanoma with 309 women matched for age, stage, and year of diagnosis. Survival at 5 years was 97% in both groups, and the share who remained free of recurrence was 96% in both. A European study from 6 melanoma centers (Kostaki and colleagues, Journal of the European Academy of Dermatology and Venereology, 2025) looked at 1,270 women of reproductive age with melanoma, 70 of them pregnancy-associated, and found no significant difference in recurrence-free survival.
A 2026 review reached the same conclusion: pregnancy does not typically reduce melanoma survival. Where worse outcomes have been reported, the authors traced them mainly to delayed diagnosis, since a changing mole was watched instead of biopsied, and to thicker tumors at the time of diagnosis. Less is known about melanoma that has already spread, where published experience is limited to small case series, and more data is needed.
Treatment for early melanoma is the same as outside pregnancy: wide local excision, which removes the biopsy site with a margin of normal skin. This is usually done under local anesthesia.
Sentinel lymph node biopsy finds the first lymph node that drains the melanoma site and checks it for cancer cells. Surgeons offer it for thicker melanomas. The procedure normally uses 2 tracers, a radioactive one and a blue dye. In pregnancy, surgeons generally use the radioactive tracer (technetium) alone and leave out the blue dye, which carries a small risk of serious allergic reaction. The radiation dose from the tracer is low and stays mostly near the injection site. Some teams do the wide excision during pregnancy and the node biopsy after delivery, and the choice depends on tumor thickness, trimester, and the patient's preference.
When imaging is needed, ultrasound and MRI are preferred because they involve no ionizing radiation. CT and PET scans are generally avoided or postponed.
Advanced melanoma during pregnancy is uncommon and harder to manage. Immunotherapy and targeted drugs can harm a developing baby, so they are generally not given during pregnancy. A team that includes a medical oncologist, a high-risk obstetrician, and a surgeon plans treatment and the timing of delivery case by case. Spread of melanoma to the placenta or the baby is rare, even when the mother has stage IV disease.
Experts quoted by the Skin Cancer Foundation say there is no evidence that a later pregnancy raises the chance of melanoma returning. The question is timing. Most recurrences happen within 2 to 3 years of diagnosis, and treatment for a recurrence, such as immunotherapy, is difficult during pregnancy.
For a thin, early-stage melanoma with a very low risk of spread, doctors often see no reason to delay. For thicker or higher-stage melanoma, many suggest waiting 2 to 3 years, which also leaves room to complete any adjuvant (post-surgery) drug treatment. Immunotherapy can sometimes affect the thyroid, pituitary, and other hormone glands in ways that influence fertility, so people about to start it may want to ask about egg, embryo, or sperm freezing first.
Age, stage, and personal priorities all enter this decision, which makes it a conversation for you and your care team. Breastfeeding is usually fine after a melanoma that was treated successfully with surgery.
