Cortisol in pregnancy: what changes, what tests show and what to ask

Cortisol normally rises during pregnancy. That is expected, and it changes how a cortisol blood test reads. This page explains the rise, why a single blood result is hard to interpret in pregnancy, what happens when someone has adrenal insufficiency, and what is known about cortisol after birth and in breast milk. It explains. It doesn’t tell you what your own result means.

If you are pregnant, have adrenal insufficiency or take a steroid medicine, and you are vomiting and can’t keep your medicine down, get urgent medical care. Call 911 or go to the emergency room if you are very weak or faint. See adrenal crisis.

What happens to cortisol in pregnancy

A 2016 systematic review explains part of the reason. The placenta is a major endocrine organ. As it develops, it makes CRH, the same signaling hormone the hypothalamus makes to start the cortisol chain. In the placenta, the mother’s cortisol stimulates more CRH rather than switching it off, the opposite of the usual feedback. The review says placental CRH and maternal cortisol rise through pregnancy.

A 2025 paper in the journal BJOG refers to physiological increases in both total and free cortisol during pregnancy. So the rise is not only a measurement effect. Some of it is active cortisol.

Separately, high estrogen in pregnancy raises the liver’s production of cortisol-binding globulin, the protein that carries cortisol in blood. A 2024 paper in the Journal of the Endocrine Society says pregnancy causes total cortisol rises similar to the roughly 67% rise it describes in women who take the pill. A 2024 review in Endocrine Reviews says the same about pregnancy and oral estrogens: they give a falsely elevated total cortisol.

We don’t give normal ranges by trimester, because we found no approved source for them. Labs also differ in method and print their own ranges.

Why a blood cortisol is hard to read in pregnancy

MedlinePlus lists pregnancy among the things that can affect cortisol levels, and says an abnormal result doesn’t always mean a condition that needs treatment. Several reviews explain why.

• Total cortisol is higher because of the carrier protein, even with no problem.
• The 2024 Journal of the Endocrine Society paper says this can cause false-positive results on baseline and dexamethasone-suppressed serum cortisol, tests used when too much cortisol is suspected. It adds that tests of free cortisol, in urine or saliva, aren’t affected by pregnancy.
• A 2023 laboratory review says a 24-hour urinary free cortisol is useful in pregnant people for this reason, and that a midnight saliva test may suit pregnancy. It says the overnight dexamethasone test is recommended as a first-line test except in pregnancy.

All of these are tests a clinician orders for a reason. A blood cortisol you order yourself, with no clinical question behind it, can’t tell you whether your pregnancy is normal. If you have symptoms that worry you, such as extreme tiredness, vomiting you can’t control or dizziness on standing, talk to your obstetric provider. We don’t link a test on this page.

Adrenal insufficiency and pregnancy

Adrenal insufficiency is a condition in which the adrenal glands don’t make enough cortisol. People with it can have healthy pregnancies, but the care is closer than usual.

NIDDK says care is planned by the doctor. If nausea and vomiting early in pregnancy make it hard to take medicine by mouth, the doctor may give corticosteroid shots. Delivery is treated like surgery, and after delivery the doctor slowly lowers the dose. NIDDK says the usual dose resumes about 10 days after the baby is born.

A 2025 multicentre audit in the UK and Ireland looked at 101 pregnancies in 79 women with primary adrenal insufficiency.

• 19 women (24%) had an adrenal crisis during pregnancy. The authors attributed 9 of those 19 to severe nausea and vomiting, and 5 to urinary tract infection. More than half happened in the first trimester.
• Steroid emergency cards were carried in only 40 of the 101 pregnancies.
• The authors say the outcome of pregnancy was generally favourable, with high rates of caesarean birth and preterm birth.

The authors say guidance on dosing in pregnancy is largely expert consensus with little published evidence, and that recommendations need strengthening. That is for the care team. If you have adrenal insufficiency and are pregnant, never change a steroid dose yourself. The authors recommend that both endocrine and obstetric teams make sure pregnant women carry a steroid warning card, and that anyone who can’t take their prescribed steroid because of vomiting seeks urgent medical review.

After birth

The weeks after birth bring their own changes. For people with adrenal insufficiency, the care team manages the dose, as above.

For mood, a 2016 systematic review of 47 studies on cortisol and perinatal depression found considerable variation in methods, samples and outcomes, and called for better measurement. There’s no simple cortisol number that tells you about your mood. If you feel low, anxious or unable to cope during pregnancy or after birth, that deserves care on its own. Talk to your obstetric provider.

Cortisol in breast milk

Yes, cortisol passes into breast milk. A 2022 study explains that breast milk contains cortisol, cortisone (the inactive form) and corticosterone, and that cortisone is the main one. These compounds cross into milk by diffusion from the blood, and milk levels follow the mother’s own daily rhythm and correlate with blood and saliva levels.

What this means for a baby is not settled. The 2022 authors say earlier studies gave contradictory results. In their own study of 38 healthy mothers, tested at one, three and six months, breast milk cortisol was not tied to maternal or infant characteristics (apart from some differences by season), and had limited influence on milk protein and no confirmed link to infant development. That is a small study. We found nothing in our approved sources that would make you change how you feed your baby because of your cortisol. If you take a steroid or other medicine and are breastfeeding, ask your prescriber.

Common questions

What is a normal cortisol level during pregnancy?

We don’t give one. It depends on the trimester, time of day, lab method and whether total or free cortisol is measured. Your lab’s printed range was not necessarily built for pregnancy. Ask the clinician who ordered the test. The normal range page covers what’s published for adults in general.

Does cortisol during pregnancy harm the baby?

This page doesn’t cover how stress or cortisol relates to pregnancy outcomes, because we couldn’t support claims from approved sources. The rise in a normal pregnancy is an expected change. If stress, sleep or mood are a concern, talk to your obstetric provider.

Should I order a cortisol test while pregnant?

Not on your own. A single result is hard to read in pregnancy and can’t diagnose a problem. If a clinician suspects one, they choose the test and read it in context.