Breastfeeding Hormones: Estrogen

71604480 Vast Photography Getty, Newborn Breastfeeding
Once your baby is born, estrogen levels drop and milk production begins. Vast Photography/Getty Images

What is Estrogen?

Estrogen is a group of naturally occurring hormones present in the human body. It is produced by the ovaries, and it is also produded by the placenta during pregnancy. Estrogen has many functions within the female reproductive system, It plays an important role in the menstrual cycle, pregnancy, and breastfeeding.

Estrogen is also known as estradiol, estrone, and estriol.

Estrogen is responsible for:

  • the onset of puberty
  • the development of secondary sex characteristics in women, such as the breasts, hair under the arms, and hair in the pubic area.
  • the development of the uterus and the vagina
  • the growth of the uterine lining during the menstrual cycle
  • vaginal lubrication
  • the prevention of ovulation and menstruation during pregnancy
  • the growth and development of the milk ducts and the milk-making tissue inside the breasts
  • triggering the onset of milk production after childbirth

Estrogen and Breastfeeding

During pregnancy, the estrogen levels in your body rise. Estrogen stimulates the growth of the milk ducts and the milk glands within your breasts, and it's responsible for preparing your breasts to produce breast milk.

Also, along with the hormone progesterone, estrogen prevents the production of breast milk while you're pregnant. Once you deliver your baby, the estrogen and progesterone levels in your body drop quickly.

This drop signals the release of the hormone prolactin, and milk production begins. However, if any of the placenta remains inside of your uterus after childbirth, then the progesterone and estrogen levels will not fall, and milk production will be delayed until the placenta is removed.

If you breastfeed, the estrogen levels in your body will remain low.

Low levels of estrogen can cause a decrease in your sex drive, vaginal dryness, and painful intercourse. Low levels of estrogen can also keep your menstrual cycle, and your fertility, from returning. If you want to become pregnant again right away, it may be difficult while you're breastfeeding. But, this doesn't mean that it isn't possible to get pregnant. You can certainly get pregnant and carry a baby to full term, even if you're breastfeeding.

See Also: Sex and Breastfeeding For Nursing Mothers

What About Birth Control?

There are many different types of birth control. Hormonal methods that contain estrogen are very effective. However, they can cause a decrease in your breast milk supply, especially if they're started in the early postpartum period. If possible, use other forms of contraception, such as non-hormonal or progestin-only methods. If you cannot avoid using hormonal birth control that contains estrogen, wait until your milk supply is well established, at about 6 weeks postpartum, before you begin to use it.




Lawrence, Ruth A., MD, Lawrence, Robert M., MD. Breastfeeding A Guide For The Medical Profession Seventh Edition.  Mosby. 2011.

Riordan, J., and Wambach, K. Breastfeeding and Human Lactation Fourth Edition. Jones and Bartlett Learning. 2014.

Hale, Thomas W., and Rowe, Hilary E. Medications and Mothers' Milk: A Manual of Lactational Pharmacology Sixteenth Edition. Hale Publishing. 2014.

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