What happens to estrogen levels postpartum?

From the Guidelines

Estrogen levels drop dramatically after childbirth, plummeting by approximately 95% within 24 hours after delivery, and reaching non-pregnant levels by 1-2 weeks after birth. During pregnancy, estrogen levels are extremely high due to production by the placenta, but this rapid hormonal decline continues over the first week postpartum 1. For breastfeeding mothers, estrogen levels remain suppressed longer due to prolactin's inhibitory effect on ovarian function. Non-breastfeeding mothers typically see estrogen levels begin to rise again around 4-6 weeks postpartum as ovulation resumes. This sudden hormonal withdrawal contributes to postpartum mood changes, night sweats, and vaginal dryness that many women experience. The low estrogen state also allows prolactin to effectively stimulate milk production in breastfeeding mothers.

Key Points

• Estrogen levels drop dramatically after childbirth
• Estrogen levels reach non-pregnant levels by 1-2 weeks after birth
• Breastfeeding mothers have suppressed estrogen levels due to prolactin's inhibitory effect on ovarian function
• Non-breastfeeding mothers see estrogen levels rise again around 4-6 weeks postpartum
• Estrogen levels will not fully normalize to pre-pregnancy patterns until regular menstrual cycles resume, which occurs on average around 6-8 weeks postpartum for non-lactating women and can be delayed for months in exclusively breastfeeding mothers 1. Some studies suggest that estrogen-containing contraceptives should be deferred until at least three or up to six weeks postpartum, partly because of the risk of venous thromboembolism 1.

From the Research

Estrogen Levels Postpartum

• Estrogen levels drop significantly postpartum, with a 100- to 1000-fold decrease during the first 3 to 4 days after delivery 2.
• This drastic decline in estrogen levels is associated with an increased risk of postpartum depression and mood changes 2, 3, 4.
• The drop in estrogen levels postpartum is also linked to changes in bone turnover, with bone mineral density decreasing during postpartum amenorrhea and recovering after resumption of menses 5.

Factors Influencing Estrogen Levels

• Lactation and hormonal status modulate bone turnover marker levels, with estrogen having a specific influence on bone turnover during the first months of lactation 5.
• Maternal age, parity, and history of previous lactation are associated with changes in bone turnover marker levels postpartum 5.
• Estrogen withdrawal postpartum increases anxiety-like behavior in animal models, with oxytocin neuroplasticity playing a role in this process 3.

Hormonal Changes Postpartum

• Postpartum women have significantly higher levels of cortisol, prolactin, thyroxine, and estrogen compared to non-puerperal women 4.
• Women with postpartum depression have lower plasma prolactin levels and higher progesterone levels compared to those without depression 4.
• Breastfeeding is associated with lower symptoms of depression and higher plasma prolactin levels postpartum 4.