Contraception and Lactation

Joyce King, CNM, FNP, PhD

J Midwifery Womens Health. 2007;52(6):614-620.

Physiology of Lactation

The two primary hormones that are needed for lactation are prolactin and oxytocin. Prolactin stimulates milk biosynthesis within the alveolar cells of the breast and oxytocin stimulates contraction of the myoepithelial cells that surround the alveoli, causing the milk to be ejected into the ducts leading to the nipple. Breast growth is stimulated by increasing prolactin secretion throughout pregnancy. Lactation is inhibited during pregnancy by progesterone produced by the placenta. Progesterone interferes with prolactin binding to the receptors on the alveolar cells within the breast, thereby directly suppressing milk production.^[5,6] The hormonal trigger for the initiation of lactation after birth is primarily the rapid decline in the level of placental progesterone. Pharmacologic levels of estrogen (estrogen from exogenous sources vs. endogenous sources) also block prolactin activity.^[5,6]

Milk secretion begins 3 to 4 days postpartum, after the steroid hormones have been cleared from maternal circulation. Suckling stimulates an increase in prolactin levels, which is important for the initiation of milk production as well as the maintenance of milk production once lactation has been established. The amount of milk produced is correlated with the amount that is removed with suckling. The optimal quantity and quality of breast milk are also dependent on other factors, such as the availability of thyroid hormone, insulin and insulin-like growth factors, cortisol, and the intake of nutrients and fluids.^[5,6]

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Cite this: Contraception and Lactation - Medscape - Nov 01, 2007.

Abstract and Introduction
Physiology of Lactation
Contraceptive Effect of Lactation
Early Initiation of a Contraceptive Method
Methods of Contraception
References

Table 1. ACOG and WHO Recommendations for Hormonal Contraception Used by Breastfeeding Women
ACOG	WHO
Progestin-only oral contraceptives prescribed or dispensed at discharge from the hospital to be started 2-3 weeks postpartum (e.g., the first Sunday after the newborn is 2 weeks old). Depot medroxyprogesterone acetate initiated at 6 weeks postpartum* Hormonal implants inserted at 6 weeks postpartum* The levonorgestrel intrauterine system can be inserted at 6 weeks postpartum. Combined estrogen-progestin contraceptives, if prescribed, typically should not be started before 6 weeks postpartum, and only when lactation is well established and the infant's nutritional status is appropriate	Progestin-only methods of contraception (i.e., oral contraceptives, levonorgestrel-IUD, levonorgestrel implant, Depo-Provera injection) are not usually recommended before 6 weeks postpartum unless other more appropriate methods are not available or not acceptable. Progestin-only methods can be used in any circumstances after 6 weeks postpartum. Combined estrogen-progestin contraceptives (i.e., oral contraceptives, transdermal path, or vaginal ring) are not to be used before 6 weeks postpartum. Combined estrogen-progestin contraceptives are not usually recommended between 6 weeks and 6 months postpartum unless other more appropriate methods are not available or not acceptable. Combined estrogen-progestin contraceptives can be generally used after 6 months postpartum

ACOG = American College of Obstetricians and Gynecologists; IUD = intrauterine device; WHO = World Health Organization.
Adapted from ACOG^[36] and WHO.^[35]
*There are certain clinical situations in which earlier initiation might be considered.

Table 2. Clinical Guidelines for Contraceptive Initiation and Use in Breastfeeding Women
Breastfeeding women should receive information about all methods of contraception to assist them in their choice of an appropriate method.
Breastfeeding women should be advised that breastfeeding delays the return of both ovulation and menstruation.
Breastfeeding women should be advised that if they are < 6 months postpartum, amenorrheic, and exclusively breastfeeding that their risk of pregnancy is approximately 2%.
Breastfeeding women need to be advised that the risk of pregnancy increases when they are beyond 6 months postpartum, or if menstruation recurs, or if they begin to supplement breastfeeding.
Breastfeeding women should be advised that the current evidence indicates that progestin-only contraceptives do not appear to have an adverse effect on breast milk volume during the first 6 weeks postpartum and also have no adverse effect on infant growth and development throughout the duration of their use.
Breastfeeding women may choose to use a progestin-only method of contraception before 6 weeks postpartum if they are at risk for ovulation and an unplanned pregnancy and no other method of contraception is acceptable.
Breastfeeding women should be advised to avoid combined hormonal contraception for at least the first 6 months postpartum.
Breastfeeding women can use both types of intrauterine devices, although insertion should be delayed until uterine involution is complete (approximately 6 weeks postpartum).
Breastfeeding women should be advised that barrier methods of contraception and fertility awareness can be utilized while breastfeeding. These methods may be more effective in breastfeeding women since breastfeeding is already associated with reduced fertility.
Breastfeeding women should be advised that they can return at any time if contraceptive side effects occur or if they want to change their contraceptive method.

Adapted with permission from FFPRHC Guidance, July 2004.^[37]

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Contraception and Lactation

Physiology of Lactation

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