Polycystic ovary syndrome (PCOS) affects pregnancy at nearly every stage, from making it harder to conceive to raising the risk of complications like gestational diabetes and preterm birth. The good news is that most women with PCOS do carry pregnancies successfully, but understanding what to watch for can help you prepare and work with your care team to reduce risks.
Why PCOS Makes It Harder to Get Pregnant
The core fertility issue in PCOS is irregular or absent ovulation. Without releasing an egg on a predictable cycle, conception becomes a matter of timing and luck. The hormonal chain behind this starts in the brain: women with PCOS tend to have rapid pulses of the hormone that controls the pituitary gland, which pushes LH levels high relative to FSH. That imbalance disrupts the normal follicle-maturation process, so eggs begin developing but stall before release.
Insulin resistance adds another layer. High circulating insulin acts directly on the ovaries, amplifying androgen (male hormone) production and further interfering with follicle development. This is why weight management and insulin-sensitizing strategies can sometimes restore ovulation even before any fertility treatment begins. Women with PCOS who do ovulate regularly, whether naturally or with medical help, have conception rates that approach those of the general population.
Gestational Diabetes Risk
Gestational diabetes is one of the most well-documented complications of pregnancy with PCOS. Meta-analyses consistently find the risk is roughly two to four times higher than in women without PCOS. The underlying insulin resistance that drives PCOS doesn’t disappear during pregnancy. It compounds with the natural insulin resistance that all pregnancies produce in the second and third trimesters, making blood sugar harder to regulate.
Gestational diabetes screening typically happens between weeks 24 and 28, but your provider may test earlier if you have PCOS or other risk factors. If diagnosed, management usually involves dietary changes, blood sugar monitoring, and sometimes medication. Uncontrolled gestational diabetes can lead to a larger-than-average baby, which increases the chance of delivery complications.
Preeclampsia and Blood Pressure
Observational studies have long linked PCOS to higher rates of preeclampsia and pregnancy-induced hypertension. In one large study of women with PCOS, about 4% developed preeclampsia, with the risk climbing higher in women who had elevated androgen levels before conception (5% compared to 2% in PCOS women without high androgens). Multiple pregnancy, higher pre-pregnancy blood pressure, and elevated fasting glucose also independently predicted preeclampsia risk.
Interestingly, newer genetic research using a technique called Mendelian randomization suggests that PCOS itself may not directly cause hypertensive complications. Instead, the association may be driven by related factors like higher BMI, insulin resistance, or androgen levels. The practical takeaway: the risk is real, but it concentrates in women who have these additional features rather than applying equally to everyone with PCOS.
Preterm Birth and Delivery
About 10% of women with PCOS in one large cohort delivered preterm, compared to typical population rates of 5% to 8%. Higher testosterone levels and elevated fasting glucose before conception were independent predictors of early delivery. Multiple pregnancies, which are more common when fertility treatments are involved, raised preterm birth odds dramatically.
Cesarean delivery rates are also higher. Emergency cesarean sections occurred in about 21% of PCOS pregnancies compared to roughly 16% in non-PCOS pregnancies in one hospital database study, a relative risk increase of about 44%. Planned cesarean rates were essentially the same between groups. The higher emergency cesarean rate likely reflects a combination of larger babies from gestational diabetes, induction of labor for hypertensive complications, and other factors rather than PCOS itself making vaginal delivery impossible.
Miscarriage
Whether PCOS independently raises miscarriage risk remains genuinely unclear. Research has explored several plausible mechanisms: insulin resistance, elevated androgens, chronic low-grade inflammation, differences in the uterine lining’s receptivity, and poorer egg quality from disrupted follicle development. Each of these could theoretically interfere with early pregnancy, but the clinical data are conflicting enough that researchers haven’t reached consensus.
What is clearer is that some of the factors that travel with PCOS, particularly obesity and uncontrolled blood sugar, are themselves established miscarriage risk factors. Addressing those modifiable risks before conception appears to be more actionable than worrying about PCOS as an abstract diagnosis.
How Maternal Hormones May Affect the Baby Long-Term
One of the more striking areas of PCOS research involves fetal programming, the idea that a baby’s hormonal environment in the womb can shape health decades later. Animal studies in sheep and primates have shown that female offspring exposed to excess androgens during development go on to exhibit features remarkably similar to PCOS: irregular cycles, multifollicular ovaries, excess visceral fat, and insulin problems. Primate studies found these effects appeared even when androgen levels normalized after birth.
In humans, women who were exposed to high androgens in utero due to other conditions (like congenital adrenal hyperplasia) develop PCOS-like features in adulthood at higher-than-expected rates. This raises the possibility that PCOS can, in some sense, pass from mother to daughter through hormonal exposure rather than purely through genetics. Research in this area is still building, but it adds another reason to manage androgen and metabolic health during pregnancy when possible.
Weight Gain During Pregnancy
There are no PCOS-specific weight gain targets during pregnancy. Current guidance says women with PCOS should follow the same recommendations as the general population, which range from about 5 to 18 kilograms (11 to 40 pounds) depending on pre-pregnancy BMI. The lower end applies to women starting pregnancy at a higher BMI, and the upper end to those who are underweight.
Reaching a healthy weight before conception is consistently emphasized as one of the most impactful things women with PCOS can do. Excess gestational weight gain is more common in PCOS and compounds the existing risks for gestational diabetes, preeclampsia, and cesarean delivery. Staying physically active and following a balanced diet during pregnancy are the primary strategies, as no PCOS-specific interventions have been established.
Metformin During Pregnancy
Metformin is widely used to manage PCOS before pregnancy, but its role during pregnancy is more limited. According to the 2023 international evidence-based guidelines for PCOS, metformin during pregnancy has not been shown to prevent gestational diabetes, late miscarriage, preeclampsia, or excessively large babies. It may, however, help reduce the risk of preterm delivery and limit excess weight gain during pregnancy in some cases.
One consideration flagged in the guidelines: children exposed to metformin in utero may have slightly higher body weight in childhood, though it’s not certain whether the medication itself is the cause. Side effects for the mother are generally mild and limited to temporary digestive discomfort. Whether to continue metformin into pregnancy is a decision that depends on individual risk factors rather than a blanket recommendation.
Breastfeeding Challenges
PCOS can affect milk supply after delivery, though experiences vary widely. In one survey of mothers with PCOS, about a third reported insufficient milk production, and most of that group produced very little at all. On the other end, about one in five mothers with adequate supply actually reported overproduction.
The hormonal explanation involves several overlapping factors. Progesterone deficiency, which is common in PCOS, may limit the breast tissue development that normally occurs during adolescence and pregnancy. High androgen levels can reduce the number of receptors for estrogen and prolactin, the hormones that drive milk production. So even when hormone levels are adequate, the breast tissue may not respond fully. If you have PCOS and plan to breastfeed, working with a lactation consultant early, ideally before delivery, can help identify supply issues quickly and set up a plan that works for you.