Normal Progesterone Levels During Breastfeeding
Progesterone plays an important role during pregnancy. After delivery of the baby, the levels of this hormone begin to drop.
Breastfeeding causes low levels of progesterone due to the effect of prolactin, which prevents ovulation.
Thus, progesterone levels tend to be very low during this time. When a mother stops lactating, prolactin levels fall, ovulation resumes and progesterone forms again.
Actions of Progesterone
Progesterone normally forms in the second half of the menstrual cycle, after ovulation.
The most important function of progesterone is to cause changes in a woman's uterus and genital tract to allow for fertilization and implantation of her egg. At the end of each cycle, progesterone levels fall; when this happens, the excess tissue in the uterus is shed, leading to menstruation. Progesterone causes other effects as well, including growth of the breast, fluid retention and a slight rise in body temperature.
- Progesterone normally forms in the second half of the menstrual cycle, after ovulation.
- At the end of each cycle, progesterone levels fall; when this happens, the excess tissue in the uterus is shed, leading to menstruation.
Removal of Placenta
The Effects of Progesterone on the Breasts
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Estrogen combines with progesterone to facilitate development of the uterus and growth of the breast. Progesterone is thought to play a role in preventing the uterus from contracting, thereby preventing premature delivery. Immediately after delivery of a baby, the levels of these maternal hormones fall drastically.
Much of the progesterone formed during pregnancy is formed by the placenta. Removal of the placenta removes the source of progesterone, and levels begin to fall.
- Estrogen combines with progesterone to facilitate development of the uterus and growth of the breast.
- Removal of the placenta removes the source of progesterone, and levels begin to fall.
Breastfeeding and Progesterone
During pregnancy, the breasts grow in size due to the action of estrogen and progesterone. Milk secretion, however, begins only after delivery of the baby. Lactation is controlled by two hormones, prolactin and oxytocin. Milk forms because of prolactin, which is made in the mother's pituitary gland.
The release of milk by an infant's suckling is due to another hormone, oxytocin.
Besides its role in milk formation, prolactin also acts on the pituitary.
There, it blocks the release of follicle-stimulating hormone, or FSH, and leutenizing hormone, or LH. These two hormones are responsible for stimulating the ovary to form follicles that ovulate. Neither estrogen nor progesterone forms during this time. Because ovulation is prevented during this time, breastfeeding can be a moderately effective form of contraception 3.
- During pregnancy, the breasts grow in size due to the action of estrogen and progesterone.
- The release of milk by an infant's suckling is due to another hormone, oxytocin.
Progesterone Levels
Decreased Milk Supply & Mirena
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Because of the action of the breastfeeding hormone prolactin, the levels of progesterone are low during lactation. Doctors rarely measure these levels of progesterone; however, during the first few weeks of breastfeeding, they are less than 5 nanograms per milliliter. After about six to 10 weeks of breastfeeding, they may range from 5 to 10 ng per ml. In contrast, progesterone levels usually rise to more than 15 ng per ml during the second half of an ovulating woman's cycle.
- Because of the action of the breastfeeding hormone prolactin, the levels of progesterone are low during lactation.
- Doctors rarely measure these levels of progesterone; however, during the first few weeks of breastfeeding, they are less than 5 nanograms per milliliter.
Resumption of Ovulation
When a mother stops breastfeeding, her levels of prolactin begin to fall. This leads to a rise in FSH and LH, allowing the resumption of menstrual cycles.
FSH and LH act on the ovaries to stimulate production of follicles.
Once a follicle is fully formed, the egg is released through ovulation. The part of the follicle left behind forms the corpus luteum, which functions to form progesterone.
- When a mother stops breastfeeding, her levels of prolactin begin to fall.
- This leads to a rise in FSH and LH, allowing the resumption of menstrual cycles.
Related Articles
References
- "Physiology"; Linda Costanzo; 2009
- "Textbook of Medical Physiology"; John Hall; 2010
- "The Journal of Steroid Biochemistry and Molecular Biology"; "The Recovery of Ovarian Function During Breastfeeding"; Mamdouh M. Shabaan et. al.; 1987
- Reed BG, Carr BR. The Normal Menstrual Cycle and the Control of Ovulation. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc. 2018
- Kumar, P., & Magon, N. (2012). Hormones in pregnancy. Nigerian Medical Journal : Journal of the Nigeria Medical Association, 53(4), 179–183. doi:10.4103/0300-1652.107549
- Norwitz ER, Caughey AB. Progesterone supplementation and the prevention of preterm birth. Rev Obstet Gynecol. 2011;4(2):60–72. PMID: 22102929
- Macias, H., & Hinck, L. Mammary Gland Development. Wiley Interdisciplinary Reviews. Developmental Biology, 1(4), 533–557. 2012 doi:10.1002/wdev.35
- Regidor PA. Progesterone in Peri- and Postmenopause: A Review. Geburtshilfe Frauenheilkd. 2014;74(11):995–1002. doi:10.1055/s-0034-1383297
- Regidor PA. The clinical relevance of progestogens in hormonal contraception: Present status and future developments. Oncotarget. 2018;9(77):34628–34638. Published 2018 Oct 2. doi:10.18632/oncotarget.26015
- Chandra V, Kim JJ, Benbrook DM, Dwivedi A, Rai R. Therapeutic options for management of endometrial hyperplasia. J Gynecol Oncol. 2016;27(1):e8. doi:10.3802/jgo.2016.27.e8
- Backstrom T, Bixo M, Stromberg J. (2015). GABAA Receptor-Modulating Steroids in Relation to Women's Behavioral Health. Curr Psychiatry Rep.17(11):92 doi: 10.1007/s11920-015-0627-4
Writer Bio
Sriram Ramgopal is a medical graduate from Sri Ramachandra University, India. He currently lives in the the greater Boston area and works as a Neurology Research Fellow at Children's Hospital, Boston. Ramgopal is also the co-founder of Sangam India, a nonprofit urban development organization based in Chennai, India.