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Development in the Womb

A baby girl’s development in the womb significantly affects her chances of having PCOS as an adult. There are two ways a baby’s development while in the womb can later affect the baby girl as an adult.

The baby’s womb environment is heavily influenced by what’s going on in the mother’s body, especially her hormone balance, and pregnant women with PCOS have:

  1. Elevated androgens, particularly testosterone
  2. Elevated AMH (Anti-Mullerian Hormone)

Elevated fetal androgens

Abnormally high testosterone levels in the womb change a range of gene expressions rather than genes themselves. Genetics is a crucial issue for all diseases, and despite no genes being found to cause PCOS directly, all genes behave differently when they’re exposed to stress, hormones or chemicals. The changes are called “gene expression”, and it’s a bit like turning sections of genetic material “On” or “Off”. Elevated testosterone alters the expression of essential genes that regulate: i

  • Mitochondrial function and efficiency
  • Fetal development of ovaries and testes
  • Egg maturation
  • Metabolism
  • Blood vessel formation
  • PCOS

Research indicates elevated testosterone alters how a fetus develops in the womb and significantly predisposes her towards PCOS, even though the condition doesn’t present until puberty. 

Another effect of elevated testosterone in the womb is that girls are more likely to have a masculine pattern of abdominal fat distribution, which increases the risk of insulin resistance and low-grade inflammation.

Alterations in mitochondrial function and reductions in their efficiency effects health way beyond fertility. Mitochondria are small structures within cells that produce all the energy in the body, and elevated testosterone in females:

  • Reduces mitochondrial efficiency
  • Increases the oxygen requirement of mitochondria

The combination of these factors makes exercising more difficult because fatigue will set in earlier and be extreme. Not enjoying exercising and finding it more difficult for other children or adults makes keeping a healthy weight more difficult.

Elevated fetal AMH

The AMH levels of women with PCOS are typically two to three times the norm, and recent research has shown AMH directly affects the hypothalamus gland, which is the “control box” for most hormonal pathways, including:

  • Sex hormones
  • Thyroid hormones
  • Adrenal hormones
  • The sympathetic nervous system

Elevated AMH in the womb increases the activity of hypothalamic cells that make GnRH cells once the girl reaches adulthood. The GnRH increases LH production from the pituitary, which stimulates more testosterone from the ovaries, which disrupts fertility and causes various PCOS symptoms. ii

Abnormal sex hormones in the womb can push a baby girl towards either PCOS or endometriosis as an adult. These two conditions have almost polar opposite hormone profiles in the womb environment, which shows how incredibly important this window of time is for female health and fertility. 

Pattern Endometriosis PCOS
Onset of periods Early Late
Menopause Early Late
Length of the menstrual cycle Short Long
Quantity of menstrual blood Heavy Light
Testosterone level Low High
Luteinizing hormone (LH) level Low High
Follicle-stimulating hormone (FSH) level High Low
Anti-Mullerian hormone (AMH) level Low High
GnRH secretions from the hypothalamus Low High



i Barsky M, Merkison J, Hosseinzadeh P, Yang L, Bruno-Gaston J, Dunn J, Gibbons W, Blesson CS. Fetal programming of polycystic ovary syndrome: Effects of androgen exposure on prenatal ovarian development. J Steroid Biochem Mol Biol. 2021 Mar;207:105830. doi: 10.1016/j.jsbmb.2021.105830. Epub 2021 Jan 27. PMID: 33515680; PMCID: PMC8056856.
ii Tata, B., Mimouni, N., Barbotin, AL. et al. Elevated prenatal anti-Müllerian hormone reprograms the fetus and induces polycystic ovary syndrome in adulthood. Nat Med 24, 834–846 (2018). https://doi.org/10.1038/s41591-018-0035-5