From the Guidelines
Breastfeeding with low FSH and estradiol levels can temporarily impact fertility due to the natural suppression of reproductive hormones during lactation amenorrhea. During lactation, prolactin levels remain elevated, which naturally suppresses FSH and estradiol production, creating a state of relative infertility that serves as a natural form of birth control called lactational amenorrhea 1. This method is most effective when a woman is exclusively breastfeeding, nursing at least every 4 hours during the day and every 6 hours at night, and her menstrual period has not returned.
Key Points to Consider
- The suppression of reproductive hormones during breastfeeding is temporary, and fertility will gradually return as breastfeeding frequency decreases or as the baby grows and nurses less often.
- Women who wish to avoid pregnancy should not rely solely on breastfeeding for contraception beyond 6 months postpartum and should discuss additional birth control options with their healthcare provider.
- The natural contraceptive effect of breastfeeding typically only lasts for the first 6 months postpartum and becomes less reliable once supplemental feeding begins or menstruation resumes.
Impact on Fertility
The impact of breastfeeding on fertility is a temporary and reversible effect, and women can expect their fertility to return to normal once they stop breastfeeding or reduce the frequency of breastfeeding. It is essential for women to discuss their fertility plans and birth control options with their healthcare provider to ensure they are using an effective method of contraception.
Hormonal Changes During Breastfeeding
Hormonal changes during breastfeeding, including elevated prolactin levels and suppressed estradiol and progesterone levels, play a crucial role in the temporary impact on fertility 1. Understanding these hormonal changes can help women make informed decisions about their reproductive health and birth control options.
From the Research
Impact of Breastfeeding on Fertility with Low FSH and Estradiol Levels
- Breastfeeding can impact fertility by suppressing ovarian activity, which is related to the enhancement of the sensitivity of the GnRH system to the negative feedback effects of estradiol 2.
- Low levels of FSH and estradiol during breastfeeding can delay the resumption of normal ovarian cycles by disrupting the pattern of pulsatile release of GnRH from the hypothalamus and hence LH from the pituitary 3.
- The plasma concentrations of FSH during lactation are sufficient to induce follicle growth, but the inadequate pulsatile LH signal results in reduced estradiol production by these follicles 3.
- Breastfeeding women with low FSH and estradiol levels may experience a suppression of ovarian activity, as measured by inhibins B and A, by reducing the secretion of LH and FSH 2.
Mechanisms Underlying Lactational Amenorrhea
- The mechanism of suckling-induced disruption of GnRH release remains unknown, but it does not appear to involve prolactin, dopamine, or opiates alone 3.
- Prolactin is the major hormone responsible for milk production and is present in sufficient quantities in almost all women to allow the establishment of normal lactation 3.
- The successful initiation of lactation, which would lead to the potential of utilizing breastfeeding as a contraceptive, may require more attention to be paid to the establishment of non-stress release of oxytocin 3.
Hormonal Changes During Breastfeeding
- Plasma prolactin levels are raised in breastfeeding mothers, which can delay the return of ovulation by inhibiting the ovarian response to FSH stimulation 4.
- FSH levels remain constant throughout the postpartum period, while mean concentrations of prolactin fall as ovarian activity returns to normal 5.
- Basal LH levels do not rise to normal levels during lactation until the resumption of normal ovulatory cycles 6.
- The resumption of follicular development is not accompanied by any increase in levels of either LH or FSH when compared with the phase of complete suppression 6.