What hormone is high during postpartum? Prolactin. It rises to support milk production and tends to stay high while breastfeeding continues, easing gradually over time. Oxytocin also rises with nursing and skin-to-skin contact. At the same time, estrogen and progesterone fall quickly once the placenta is delivered. This shift, high prolactin against low estrogen and progesterone, may contribute to much of how a new mother feels in the first weeks, though recovery, sleep, and support all play a part.
This is normal physiology, not a disorder. Knowing which hormones move, how far, and for how long separates an expected change from a sign worth checking. Marek Diagnostics offers direct-access hormone panels that measure these levels, so this guide maps the shifts week by week and shows where a test fits.
What hormone is high during postpartum?
During postpartum, prolactin is the hormone that stays high. Released by the pituitary gland, it drives milk production and rises in proportion to how often a baby feeds. Oxytocin also surges with nursing. Estrogen and progesterone, high all through pregnancy, drop sharply after delivery.
Prolactin runs well above pre-pregnancy levels in breastfeeding women and eases as feeds space out, with wide variation between mothers (Stuebe et al., 2015). It is high in late pregnancy and tends to stay high after birth in nursing mothers (Wu and Jin, 2025). A single prolactin test reflects one moment, so timing relative to the last feed matters, and results are best interpreted with a provider.
|
Hormone |
Direction after birth |
Main role |
Rough timeline |
|
Prolactin |
High |
Milk production |
Peaks early, eases as feeds space out |
|
Oxytocin |
High in pulses |
Milk let-down, uterine contraction |
Spikes with each feed |
|
Estrogen (estradiol) |
Low |
Reproductive cycle |
Drops within days, low while nursing |
|
Progesterone |
Low |
Pregnancy maintenance |
Falls to pre-pregnancy level by about day 5 |
|
Cortisol |
Variable, often raised |
Stress response |
Tied to sleep loss and newborn care |
Why do estrogen and progesterone drop after birth?
They fall because their main source during pregnancy, the placenta, is gone. Estrogen can run about 100 times higher in pregnancy than baseline, then declines abruptly after delivery (Wu and Jin, 2025). Estrogen and progesterone regain their pre-pregnancy levels by about the fifth day postpartum (Wu and Jin, 2025).
That drop is what lets prolactin work. High estrogen and progesterone keep breast tissue from responding to prolactin in pregnancy; once both fall, prolactin starts milk secretion (Chauhan and Tadi, 2022). An estradiol test and a progesterone measurement show the fall in numbers.
What happens to your hormones in the first days after birth?
In the first days, prolactin climbs, oxytocin pulses with every feed, and estrogen and progesterone bottom out. Milk secretion, or lactogenesis, usually starts on the third or fourth day postpartum (Chauhan and Tadi, 2022).
Oxytocin does two jobs here. It contracts the small muscle cells around the milk ducts to push milk out, and it helps the uterus shrink back down (Chauhan and Tadi, 2022). Tearfulness and mood swings in this window are common and usually pass. They're thought to reflect the hormonal and physical changes after birth, along with factors like sleep loss, and are not anything a mother is doing wrong.
Hormone changes from weeks 3 to 6
By weeks 3 to 6, prolactin is still high but easing off its earliest peak, though it stays well above pre-pregnancy levels while nursing continues (Stuebe et al., 2015).
Broken sleep and round-the-clock newborn care are commonly linked to raised cortisol in this period. Mothers who are not breastfeeding may see early signs of their cycle returning, since prolactin is not held up by regular suckling.
Where your hormones stand at 3 months
At 3 months, prolactin is lower than in the first weeks if feeds have spaced out, though it stays above pre-pregnancy levels in mothers who breastfeed often. Estrogen stays low while nursing continues.
High prolactin is also why periods often pause. It suppresses the hormones that trigger ovulation, which produces lactational amenorrhea, the natural gap in menstruation during breastfeeding (Chauhan and Tadi, 2022). Because ovulation can return before the first period, breastfeeding alone is not a dependable form of birth control.
Hormone levels around 6 months postpartum
Around 6 months, many babies start solids, feeds drop off, and prolactin falls further. Estrogen then recovers and periods often return.
Timing varies with feeding. In breastfeeding women, menstruation usually returns at 4 to 5 months and, in some cases, as late as 24 months; women who are not breastfeeding usually cycle again by 6 to 8 weeks (Chauhan and Tadi, 2022).
When do postpartum hormones return to normal?
There is no single date. Return to a pre-pregnancy pattern is influenced largely by breastfeeding and varies from person to person. Women who do not nurse usually see cycles resume within 6 to 8 weeks, while those who breastfeed exclusively can stay in a low-estrogen, high-prolactin state for months, until feeds taper or stop (Chauhan and Tadi, 2022).
A mother still nursing every few hours at 4 months has different levels than one who weaned at 6 weeks, and both are normal. That range is why persistent symptoms are best reviewed with a provider, who can decide whether testing is helpful.
Postpartum symptoms that may warrant a hormone test
Most postpartum hormone changes are expected and settle on their own. A few are worth a closer check with a provider.
The thyroid is the most common one. Postpartum thyroiditis affects a notable minority of women within the first year after birth, sometimes as a swing from an overactive phase at 1 to 4 months to an underactive phase at 4 to 8 months (Carlson and Mikes, 2025).
Many cases settle within a year, though some women go on to lasting hypothyroidism that may need treatment (Carlson and Mikes, 2025). Because its symptoms, fatigue, mood changes, and weight shifts, can look like ordinary new-parent tiredness, a TSH test ordered by a provider can help clarify whether the thyroid is involved.
Low mood that lingers past the first couple of weeks, worsens, or affects daily care warrants prompt evaluation by a provider; any thoughts of harming yourself or your baby need immediate help.
This may be postpartum depression, which is common and treatable, and earlier support tends to help. Fatigue, low libido, and hair changes can come from the hormone shifts above, but also from anemia, thyroid changes, or sleep loss, which is why persistent symptoms are best evaluated by a provider.
How lab testing shows your postpartum hormone levels
When a provider recommends it, testing can add detail to the general pattern above. Prolactin, estradiol, progesterone, thyroid markers, and sex hormone-binding globulin come from a standard blood draw. Prolactin shifts with feeds and time of day, so a single reading is interpreted alongside how recently the baby nursed, not on its own.
Marek Diagnostics offers these as direct-access tests, so you can order a panel without a referral and review the results with your provider, who can help decide whether testing fits your situation. You can pick single markers or choose from a set of lab panels.
Ready-made lab bundles and a custom hormone panel let you group several markers around what you want to track. Understanding what hormone is high during postpartum, and what has dropped, can help you and your provider decide together whether any testing adds useful detail in your situation.
Disclaimer: This blog post is intended for informational purposes only and should not be considered medical advice. Always consult a healthcare professional before making changes to your health routine.
FAQs
What hormone is high during postpartum?
Prolactin is the hormone that stays high during postpartum. It rises to support milk production and tends to stay high while breastfeeding continues, easing gradually over time. Prolactin runs well above pre-pregnancy levels and varies widely between mothers (Stuebe et al., 2015). Oxytocin also rises with nursing.
Does prolactin stay high if you do not breastfeed?
No. In women who do not breastfeed, prolactin declines within about 3 weeks after delivery (Wu and Jin, 2025). Breastfeeding is what keeps prolactin high, because milk removal and suckling signal the pituitary to keep producing it.
Which hormones drop after birth, and how fast?
Estrogen and progesterone fall sharply once the placenta is delivered. Both regain their pre-pregnancy levels by about the fifth day postpartum (Wu and Jin, 2025). Estrogen tends to stay low the whole time a mother is breastfeeding.
When do postpartum hormones return to normal?
It is influenced largely by breastfeeding and varies from person to person. Women who do not nurse usually see their cycle return by 6 to 8 weeks, while those who breastfeed can stay in a high-prolactin, low-estrogen state for months, sometimes until 4 to 5 months or later (Chauhan and Tadi, 2022).
Can postpartum hormone changes affect the thyroid?
Yes. Postpartum thyroiditis affects a notable minority of women within the first year after birth, sometimes swinging from an overactive to an underactive phase (Carlson and Mikes, 2025). Many cases settle within a year, though some become lasting, so persistent fatigue or mood changes are worth discussing with a provider.
Should you get a lab test for postpartum hormones?
Because symptoms like fatigue, low mood, and low libido can come from hormones, thyroid changes, anemia, or sleep loss, a provider can help decide whether testing is useful. Prolactin shifts with feeds and time of day, so any results are interpreted alongside your feeding pattern and reviewed with your provider.
References
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