PCOS / PMOS
PCOS and reproduction
From trying for a baby to breastfeeding and the next generation
Polycystic ovary syndrome (PCOS/PMOS) is the most common cause of irregular or absent ovulation. Many women only learn about the diagnosis when pregnancy does not happen. Others are told at a young age that they “will not be able to have children”. This statement is wrong and causes needless worry.
The data show a different picture. Women with the syndrome often need more time to become pregnant and more often need treatment. In the end, however, most of them have children. In large long-term studies from Finland, the number of children of women with symptoms of the syndrome hardly differs from that of other women.
Reproduction in the syndrome does not end with conception. The syndrome affects the attempt to conceive, the pregnancy itself, the placenta, birth, breastfeeding and the health of the child. For this reason, care must cover this whole path.
Reproduction in the syndrome as a path
Before conception
Weight management and setting the advised weight gain for pregnancy. Assessment for metabolic syndrome, measurement of insulin resistance and blood pressure. Starting folic acid. Assessing whether the pregnancy is high-risk.
The placenta is built in the first weeks.
Pregnancy
Higher risk of miscarriage, gestational diabetes, pre-eclampsia and preterm birth.
Possibly a glucose tolerance test already before 24 to 28 weeks. Possibly aspirin in high-risk pregnancies.
Birth and breastfeeding
More cesarean sections because of complications. Breastfeeding depends mainly on a higher weight and less on the syndrome itself. Breastfeeding improves insulin sensitivity.
After gestational diabetes, pre-eclampsia or a placental disorder: follow-up programs after birth and in the following years, to reduce cardiovascular events.
The next generation
Daughters have the syndrome more often. Sons can also have hormonal and metabolic changes (male PCOS).
Good hormonal and metabolic control of the syndrome before and during pregnancy reduces more severe forms in the next generations, in daughters and in sons.
What is the ovarian reserve like in the syndrome?
Women with the syndrome have more small follicles than other women of the same age. This is why the hormone AMH, which reflects the ovarian reserve, is often two to three times higher than usual. Studies also show that the ovarian reserve in the syndrome falls more slowly and that menopause often comes a little later.
This is good news, but not a guarantee. In the syndrome, too, the quality of the eggs depends mainly on age. A high AMH value does not protect against the decline in egg quality after 35, nor against the higher risk of miscarriage with rising age. A high reserve is therefore no reason to postpone the wish for a child indefinitely.
Is contraception still needed?
Rare ovulation does not mean infertility. Women with the syndrome can become pregnant even with long cycles, often at an unpredictable time. When there is no wish for a child, reliable contraception is therefore needed.
The contraceptive pill regulates the period, but it hides the syndrome. Many women only notice that their cycle is irregular when they stop the pill, often exactly when they start trying for a baby. When the syndrome has been diagnosed and its form has been classified, a woman can use a form of hormonal contraception and stop it before she starts trying for a pregnancy. In these cases, the doctor weighs the benefit of immediate hormonal support for the body, which may shorten the time to pregnancy. The final decision depends on the clinical form of the syndrome and on the individual characteristics of each woman.
What happens when trying for a baby?
The World Health Organization speaks of infertility when a couple does not achieve pregnancy after twelve months of regular sex without contraception. From the age of 35, the period is six months. With very rare or absent periods, waiting makes no sense. Without ovulation, pregnancy cannot happen, not even in twelve months. In this case, the assessment should start straight away, and it always involves both partners.
A normal cycle does not rule out the syndrome or an ovulation disorder. Some women with the syndrome have almost regular periods but do not ovulate in every cycle. There is also a form of the syndrome with regular periods and ovulation, the third phenotype. In the same way, an irregular cycle does not mean that ovulation never happens. It just happens rarely and at a time that no one can predict.
The difficulty is not only due to missing ovulation. The quality of the egg, insulin resistance, weight and the function of the lining of the womb also play a role. The causes, the assessment and the treatment, including IVF, are described in detail in the article “PCOS and infertility”.
What improves the chances?
The 2023 international guideline gives great importance to the time before pregnancy. Before any fertility treatment, the doctor should check weight, blood pressure, blood sugar, blood lipids, smoking, alcohol and mental health. For insulin resistance, the best method is a glucose tolerance test with insulin measurement. As an alternative, the specializt doctor can measure other markers that show the metabolic side of the syndrome. The doctor also sets how much weight the woman may gain in pregnancy and assesses whether the pregnancy will be high-risk.
Folic acid is important for all women with the syndrome who want to become pregnant. Because periods are irregular, a woman often notices late that she is pregnant. Taking folic acid from the start of trying means that the first and important period of the baby’s organ development is not missed.
In women with a higher weight, a weight loss of 5-10% can bring ovulation back and improve the result of treatment. Regular exercise improves insulin sensitivity, even without weight loss. However, this goal is always weighed against time. For a woman over 35, it usually makes no sense to delay treatment for many months for the sake of weight loss. In this case, both paths run in parallel.
Smoking harms eggs and sperm and shortens the fertile years. In the partner, too, weight, smoking and alcohol affect sperm quality. Preparation therefore concerns the couple and not only the woman.
What about miscarriage and recurrent miscarriage?
In many studies, women with the syndrome have a higher risk of miscarriage. The international guideline explicitly lists miscarriage among the risks of pregnancy in the syndrome. The reasons are the changed quality of the egg, a lining of the womb that responds less to progesterone, insulin resistance and a higher weight. The risk is linked more to these metabolic factors than to the appearance of the ovaries on ultrasound. According to the guideline, IVF does not raise this risk further.
In women with recurrent miscarriage, the ESHRE guideline does not recommend routine testing of all women for the syndrome. When the syndrome is present, however, insulin resistance, weight and the function of the luteal phase need attention before the next pregnancy. More in the article “Recurrent pregnancy loss”.
What does the syndrome mean for the placenta?
The placenta is the organ that nourishes the baby, and its development starts at implantation. In the syndrome, androgens, insulin and mild chronic inflammation affect the lining of the womb just when the placenta begins to form. Studies of the placenta in women with the syndrome more often show changes in its structure and blood supply.
This “placental dysfunction” largely explains why women with the syndrome more often have pre-eclampsia and problems with the baby’s growth. For the same reason, a good hormonal and metabolic state before conception matters so much. The placenta is “built” in the first weeks, often before the woman knows she is pregnant.
What are the risks in pregnancy?
In most cases, a pregnancy in the syndrome is a normal pregnancy. The risks, however, are higher than in other women. In a meta-analysis in Human Reproduction Update, women with the syndrome had about a 3 times higher risk of gestational diabetes, about a 3.5 times higher risk of high blood pressure in pregnancy and of pre-eclampsia, and about a 1.7 times higher risk of preterm birth. Their newborns more often needed care in a neonatal intensive care unit. A newer large review from 2024 confirms this picture.
These risks also exist in women with a normal weight. They rise, however, with a higher weight, with insulin resistance and in the forms with raised androgens. The baby can be smaller than expected, because of the placenta, or larger, because of gestational diabetes. Both need monitoring.
How much do the risks rise?
How many times higher the risk is than in women without the syndrome
1 = women without the syndrome
What about birth?
Women with the syndrome more often give birth by cesarean section, about 1.5 times as often as other women. The syndrome itself is not a reason for a cesarean section. Cesarean sections are more common because of pregnancy complications: pre-eclampsia, gestational diabetes, a large baby or the need to induce labor. The obstetrician who looks after the pregnancy decides on the mode of birth according to obstetric criteria.
What about breastfeeding?
Breastfeeding benefits both mother and child. In women with the syndrome, breastfeeding improves insulin sensitivity and may lower the risk of type 2 diabetes later in life. Some women with the syndrome report less milk, and androgens and insulin probably affect breast development in pregnancy. The largest study on this topic, with about 2.4 million women (Breastfeeding Medicine, 2025), found no lower or shorter breastfeeding in women with the syndrome once weight and other factors were taken into account. A higher weight was linked to less breastfeeding. Early support from a midwife or a lactation consultant helps a lot.
Is the syndrome passed on to the next generations?
The syndrome has a strong hereditary basis. In a large Swedish registry study (Nature Medicine, 2019), daughters of mothers with the syndrome had about a 5 times higher risk of being diagnosed with the syndrome themselves. Genes, however, do not explain everything. High androgen and insulin levels in the mother during pregnancy seem to affect the baby’s development and to “program” hormonal and metabolic changes for later life.
In observational studies, children of mothers with the syndrome, boys included, have a higher risk of higher weight and metabolic disorders. The hormonal and metabolic picture in sons is now recognized as a male form of the syndrome (male PCOS). Studies also show a small increase in the risk of neurodevelopmental conditions such as ADHD and autism. This link is still being studied. These data do not mean that the child will become ill. They mean that a good hormonal and metabolic state before and during pregnancy also protects the next generation.
What care is needed around birth?
Good care starts before conception and continues after birth. The guideline recommends a glucose tolerance test before pregnancy or at the first pregnancy visit, and another test at 24 to 28 weeks. In pregnancies at high risk of pre-eclampsia, the obstetrician may recommend low-dose aspirin. The doctor also carefully monitors blood pressure, weight gain and the baby’s growth, and asks about mood. It is important that the gynecologist who looks after the pregnancy knows about the diagnosis.
After birth and during breastfeeding, the cycle often returns irregularly. After gestational diabetes, a blood sugar check is needed a few weeks after birth, because the risk of type 2 diabetes later in life is higher. After gestational diabetes, pre-eclampsia or a placental disorder, a woman needs a follow-up program after birth and in the following years, to reduce cardiovascular events. The time after birth is also a vulnerable phase for mental health. For a second child, age and the experience of the first pregnancy help the couple to choose the right time.
The practice's approach
The practice sees reproduction in the syndrome as a path: from clear information at a young age and suitable contraception, to preparation before conception, pregnancy, birth and breastfeeding.
The doctor assesses phenotype, metabolism, age and ovarian reserve together. Hormonal and metabolic preparation before conception protects the placenta, the pregnancy and the health of the child.
The aim of the practice is a pregnancy at the right time, with the best possible health for mother and child, and good care that continues after birth.
Sources: International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome (Monash University, ESHRE, ASRM, 2023); Teede HJ et al., Human Reproduction 2023. Teede HJ et al., Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome, The Lancet 2026. WHO – Guideline for the prevention, diagnosis and treatment of infertility (2025). Koivunen R et al., Human Reproduction 2008 (Northern Finland Birth Cohort 1966). Boomsma CM et al., A meta-analysis of pregnancy outcomes in women with polycystic ovary syndrome, Human Reproduction Update 2006. Bahri Khomami M et al., Nature Communications 2024 (pregnancy outcomes in the syndrome). Palomba S et al., Pregnancy complications in women with polycystic ovary syndrome, Human Reproduction Update 2015. Palomba S, Piltonen TT, Giudice LC, Endometrial function in women with polycystic ovary syndrome, Human Reproduction Update 2021. ESHRE Guideline – Recurrent pregnancy loss (2022). Risal S et al., Prenatal androgen exposure and transgenerational susceptibility to polycystic ovary syndrome, Nature Medicine 2019. Joham AE et al., Obesity, polycystic ovary syndrome and breastfeeding: an observational study, Acta Obstetricia et Gynecologica Scandinavica 2016. Bui LM et al., Obesity but not polycystic ovary syndrome associated with decreased breastfeeding initiation rates, Breastfeeding Medicine 2025. Vanky E et al., Breast size increment during pregnancy and breastfeeding in mothers with polycystic ovary syndrome, BJOG 2012.