Polycystic Ovary Syndrome and Pregnancy: How Is Ovulation Tracked?

Polycystic ovary syndrome (PCOS) is a condition with hormonal and metabolic aspects that affects around 10–13% of women of reproductive age worldwide; this figure is based on prevalence studies using the diagnostic criteria accepted by the 2023 international guideline ¹. Irregular periods, signs of excess androgens (such as increased hair growth) and difficulty becoming pregnant due to ovulation problems are among the key features described by the guideline ¹. The guideline’s first message is reassuring: women with PCOS should be told that pregnancy can usually be achieved naturally or with the help of treatment ^1,2. This article summarises, in the language of the guideline, how ovulation is monitored and what the treatment steps are.

The American Society for Reproductive Medicine (ASRM) lists PCOS among the most common causes of ovulation disorders; ovulation disorders are found in about 15% of infertile couples and account for up to 40% of female infertility (in everyday terms, being unable to conceive) ³. A history of infrequent periods (oligomenorrhoea) or absent periods (amenorrhoea) is considered clinically sufficient to show that ovulation is not taking place ³. The assessment does not focus on the woman alone: because male factors are common, the male partner’s history and at least one semen analysis are obtained at the outset ³. The recommended tests to check whether the tubes (fallopian tubes) are open are an X-ray of the womb (hysterosalpingography, HSG) or sonohysterography ³; their timing is planned according to the individual history ¹.

How is PCOS diagnosed?

For diagnosis in adults, the 2023 guideline looks for two of three features: irregular menstrual cycles or ovulation problems; excess androgens shown on examination or blood tests (hyperandrogenism: increased hair growth, acne, hair loss or high testosterone); and a polycystic appearance of the ovaries on ultrasound or a high anti-Müllerian hormone (AMH) level ^1,2. If irregular periods and hyperandrogenism are both present, ultrasound or AMH is not needed; causes that can produce a similar picture, such as thyroid disease and raised prolactin, are ruled out ^1,2. To avoid overdiagnosis, ultrasound and AMH are not used together ¹.

The guideline defines “irregular cycles” in numbers: from three years after the first period, ovulation problems are considered if cycles are shorter than 21 days or longer than 35 days, or if there are fewer than eight periods a year; any single cycle lasting longer than 90 days also falls into this category ¹. In adolescents, ultrasound and AMH are not recommended for diagnosis; where the picture is unclear, the approach is to reassess within the eight years after the first period ¹. The guideline states that the diagnosis can be regarded as a lifelong condition; a lifelong health plan is therefore recommended, covering not only reproduction but also metabolic, cardiovascular and mental health ^1,2.

How is ovulation tracked?

In most women who ovulate, periods are regular and predictable; they usually come every 21–35 days, preceded by mild premenstrual symptoms such as breast tenderness, so a carefully taken menstrual history is the first clue ³. Cycles without ovulation can occasionally occur in women with regular periods too; ASRM reports that these are relatively uncommon (1–14%), while the PCOS guideline states that ovulation problems can occur even with regular cycles and that serum progesterone can be measured when needed ^1,3. For objective confirmation, a blood progesterone test about one week before the expected period is used; a value above 3 ng/mL is considered sufficient evidence of recent ovulation ³.

Home tracking methods include ovulation tests that detect the rise in LH in urine, and observing cervical mucus (secretions from the cervix); ASRM reports that these methods increase the chance of conceiving in a given cycle ⁴. Ovulation may occur within two days after the LH test turns positive; a false-positive result is seen in about 7% of cycles ⁴. In PCOS, the baseline LH level can stay persistently high, so the urine test may give a false positive ³. The calendar method and phone apps assume that cycle length is consistent ⁴; in PCOS with irregular cycles, this assumption usually does not hold. Measuring basal body temperature is considered cheap but often unreliable ³.

The fertile window and timing of intercourse

According to ASRM, the “fertile window” is the six-day interval ending on the day of ovulation; during this time, the chance of pregnancy peaks with intercourse every 1–2 days, and the results with intercourse 2–3 times a week are very close to this ⁴. Restricting frequency is not recommended; couples can set their own rhythm according to their preferences ⁴. Sexual positions and habits after intercourse (such as lying on your back) have no effect on the chance of pregnancy ⁴. For couples who cannot have regular, frequent intercourse, tracking methods can help to time intercourse within the fertile window and shorten the time to pregnancy ⁴.

If ovulation is being stimulated with treatment, monitoring is planned by the doctor. The guideline states that some oral ovulation-inducing medicines increase the risk of multiple pregnancy and that these cycles may require ultrasound monitoring ¹. With injected hormone (gonadotrophin) treatment, close ultrasound monitoring is essential; according to the guideline, if more than two (three or more) follicles larger than 14 mm in diameter develop, cancelling the cycle and avoiding unprotected intercourse is recommended ¹. Ultrasound monitoring of follicles thus takes account of both the timing of ovulation and safety. Before every ovulation induction, the possibility of an existing pregnancy is ruled out ¹.

Treatment steps: from lifestyle to IVF

The guideline recommends a lifestyle approach including healthy eating and physical activity for all women with PCOS; no particular diet has been shown to be better than others, and a healthy lifestyle is beneficial even without weight loss ^1,2. In women with excess weight, weight management is discussed before pregnancy, because it affects clinical pregnancy, miscarriage and live birth outcomes after infertility treatment; the guideline asks that this conversation avoids weight stigma and takes place with permission ^1,2. In women planning a pregnancy, blood pressure, smoking, alcohol, diet, folate supplementation, sleep and mental health are reviewed ^1,2.

Medical treatment is given in steps. For women who do not ovulate and have no other cause of infertility, the first step is the oral ovulation-inducing medicine defined in the guideline; alternative oral options and a medicine targeting insulin resistance are also compared in the guideline, and suitability is determined at the consultation ^1,2. If there is no response to the first step, injected hormone (gonadotrophin) treatment or laparoscopic ovarian surgery is the second step ^1,2. In vitro fertilisation (IVF), if there is no other compelling reason for it, may be recommended as the third step when the first and second steps have not worked; in PCOS, because of the risk of ovarian hyperstimulation syndrome, preventive options are discussed in advance ^1,2.

Monitoring before and after pregnancy

The guideline places pregnancy with PCOS in the high-risk group: the risks of gestational diabetes, high blood pressure in pregnancy and pre-eclampsia (known in everyday language as ‘toxaemia of pregnancy’), miscarriage, preterm birth, a baby small for gestational age and caesarean section are increased; on the other hand, the risk of a large baby is considered not to be increased ^1,2. For this reason, blood pressure is measured when a pregnancy is being planned, and a glucose loading test (75 g oral glucose tolerance test, OGTT) is recommended for all women who do not already have diabetes; if it was not done before pregnancy, it is done at the first antenatal appointment and repeated at weeks 24–28 ¹. Assisted reproductive techniques are thought not to add extra risk of miscarriage or preterm birth in PCOS ^1,2.

Long-term monitoring does not end with the birth. Regardless of age and body mass index, women with PCOS have a higher risk of impaired glucose tolerance and type 2 diabetes; blood sugar control (glycaemic status) is assessed at diagnosis and repeated every 1–3 years depending on individual risk factors ¹. Blood fats (lipid profile) are checked at diagnosis, and blood pressure is measured once a year ¹. Depressive and anxiety symptoms are markedly more common in PCOS; the guideline recommends that all women are screened with validated questionnaires and referred to a mental health professional when needed ^1,2. Making decisions together with the patient is a core principle of the guideline ¹.

If you have symptoms, please consult an obstetrics and gynaecology specialist.