Postpartum Hormones

What Happens to Your Hormones After Birth?

Pregnancy is one of the biggest hormonal events of a person’s life, and giving birth reverses much of it within days. The American College of Obstetricians and Gynecologists (ACOG) notes that levels of estrogen and progesterone drop sharply in the hours after childbirth, and that these changes may trigger depression in the same way smaller hormone shifts trigger mood changes before a period.

Understanding what changes, and what science actually knows about hormones and mood, can help you make sense of how you feel and avoid being misled by “hormone imbalance” products.

The Key Hormone Changes

A key point: the trigger for the big drop is delivery of the placenta, not a gradual decline during pregnancy. Progesterone stays high right up until the placenta is delivered.

In a study that measured hormones in the first six days after birth, estriol (a form of estrogen), progesterone and CRH fell rapidly, while cortisol fell only modestly. Baby blues symptoms peaked around day 5 and tracked with changes in these stress and estrogen signals.

Is There a “Postpartum Hormone Crash”?

Every new mother goes through this rapid drop. That’s why many people feel weepy, irritable or overwhelmed in the first two weeks, known as the baby blues. For most, this settles on its own.

Postpartum depression is different: it lasts longer and is more severe. And here is what surprises many people: research has not found that women with postpartum depression have abnormal hormone levels. Instead, the leading explanation is that some women are more sensitive to the normal hormone drop.

Sensitivity, Not Imbalance

The best evidence comes from a small but landmark study by researchers at the National Institute of Mental Health:

• They gave 16 women who were not pregnant high doses of estrogen and progesterone to mimic pregnancy, then stopped the hormones suddenly to mimic birth.
• 5 of 8 women with a past history of postpartum depression developed significant mood symptoms.
• None of the 8 women without that history did.

Both groups had the same hormone changes. The difference was how their brains responded. The researchers concluded that women with a history of postpartum depression are “differentially sensitive” to these hormones. The same pattern has been found in PMDD, where symptoms reflect an abnormal response to normal hormone changes.

A review of allopregnanolone research similarly found that studies disagree on whether levels differ in women with postpartum depression, but that women with a history of it appear more susceptible to the drop.

Allopregnanolone and the New PPD Medications

Allopregnanolone acts on GABA-A receptors, which calm brain activity. One theory is that after birth, the brain’s receptors don’t readjust quickly enough when allopregnanolone falls. This idea led to the first medications made specifically for postpartum depression: brexanolone, an IV form of allopregnanolone, and zuranolone (Zurzuvae), a 14-day pill. Zuranolone’s success in trials supports the theory, but doesn’t prove that low allopregnanolone causes postpartum depression.

Can a Hormone Test Diagnose Postpartum Depression?

No. No blood, saliva or urine hormone test has been shown to diagnose or predict postpartum depression. Because the problem appears to be sensitivity rather than abnormal levels, a hormone panel wouldn’t be expected to catch it.

Be cautious about products and practitioners that promise to fix a “postpartum hormone imbalance” or “adrenal fatigue” with tests and supplements. A systematic review of 58 studies concluded that adrenal fatigue is not a real medical condition and that the tests used to diagnose it gave conflicting results.

The tools that do help identify postpartum depression are questionnaires like the Edinburgh Postnatal Depression Scale and a conversation with a clinician. The one hormone-related condition worth testing for is thyroid disease; see postpartum thyroiditis.

Does Hormone Treatment Help?

• Estrogen: a 1996 randomized trial of 61 women with severe postpartum depression found that an estrogen skin patch improved depression scores faster than placebo. A Cochrane review concluded estrogen “may be of modest value” for severe postpartum depression, but the evidence is limited and it is not a standard treatment.
• Progestins: the same Cochrane review found a synthetic progestin (norethisterone) given right after birth was linked to a higher risk of postpartum depression. Natural progesterone has never been tested in a controlled trial for postpartum depression.
• Postpartum psychosis: small, uncontrolled studies have tested estrogen for postpartum psychosis, a different and rarer condition. An independent review found serious weaknesses in that research.

Proven treatments for postpartum depression include therapy, antidepressants and zuranolone.

Breastfeeding and Hormones

Breastfeeding keeps prolactin high and suppresses ovulation. The more frequently and exclusively you nurse, the longer this usually lasts. Researchers now believe suckling makes the brain more sensitive to estrogen’s signal to hold off ovulation. Full breastfeeding can suppress fertility for the first 6 to 9 months, but it is not guaranteed.

When Do Hormones Return to Normal?

• If you’re not breastfeeding: ovulation and periods usually return within 6 to 8 weeks. Most women don’t ovulate before 6 weeks.
• If you’re breastfeeding: it varies widely, from a few months to more than a year.
• You can ovulate before your first period, so pregnancy is possible before periods return.
• Thyroid function usually normalizes within weeks to months.

Weaning and Mood

Some women notice mood changes when they stop breastfeeding. Researchers have proposed that shifting allopregnanolone levels during weaning and the return of periods could affect mood in vulnerable women, and clinicians note that women with bipolar disorder can relapse around weaning. But this is a hypothesis; no large study has shown that weaning causes depression in the general population. If your mood drops when you wean, it’s still worth talking to your provider.

Hair Loss After Pregnancy

Many women notice hair shedding a few months after birth, often attributed to falling estrogen shifting hair into a resting phase. Interestingly, one review found little statistical evidence that shedding is actually greater after pregnancy, so the extent of “postpartum hair loss” is debated. What is clear is that women who notice a lot of hair loss report more anxiety, so it’s worth mentioning to your doctor if it bothers you.

When to Get Help

Hormone changes are normal, but persistent low mood, anxiety, loss of interest or thoughts of harming yourself are not something to wait out. Talk to your ob-gyn, midwife or primary care doctor if symptoms last more than two weeks.

Find a postpartum depression specialist near you

Call or text the National Maternal Mental Health Hotline at 1-833-TLC-MAMA (1-833-852-6262), 24 hours a day. If you have thoughts of harming yourself, call or text 988.

Frequently Asked Questions

What hormones drop after giving birth?

Estrogen and progesterone fall sharply once the placenta is delivered, along with allopregnanolone and the placental stress hormone CRH. Prolactin and oxytocin stay active to support breastfeeding.

Do hormones cause postpartum depression?

Hormone changes play a role, but research suggests postpartum depression reflects greater sensitivity to normal hormone changes rather than abnormal levels. Other factors such as past depression, stress and sleep loss also matter.

How long does it take for hormones to balance after pregnancy?

If you’re not breastfeeding, cycles usually return within 6 to 8 weeks. If you are, it can take months to more than a year.

Can a blood test show postpartum hormone imbalance?

No hormone test can diagnose postpartum depression. A thyroid test can rule out thyroid problems, which can cause similar symptoms.

Can weaning cause depression?

Some women notice mood changes when weaning, and there are hormonal theories for why, but this hasn’t been proven in large studies.