Exposure to contraceptive hormones through breast milk--are there long-term health and behavioral consequences?

Some evidence of effects of environmental chemicals on the endocrine system in children

Pollutant chemicals that are widespread in the environment can affect endocrine function in laboratory experiments and in wildlife. Although human beings are commonly exposed to such pollutant chemicals, the exposures are generally low and clear effects on endocrine function from such exposures have been difficult to demonstrate. Human data including both exposure to the chemical agent and the endocrine outcome are reviewed here, including age at weaning, age at puberty, anogenital distance, and sex ratio at birth, and the strength of the evidence are discussed. Although endocrine disruption in humans by pollutant chemicals remains largely undemonstrated, the underlying science is sound and the potential for such effects is real.

Levonorgestrel pharmacokinetics in plasma and milk of lactating women who take 1.5 mg for emergency contraception

BACKGROUND

Progestin-only methods are among the contraceptive options available for breastfeeding women, however the doses of progestin used in emergency contraception (EC) have not been evaluated in nursing mothers. We therefore investigated the pharmacokinetics of 1.5 mg levonorgestrel (LNG) in lactating women.

METHODS

Twelve healthy exclusively breastfeeding volunteers received 1.5 mg LNG. Women refrained from nursing for 72 h after dosing and fed their infants with milk frozen beforehand. Serial blood and milk samples were collected for 120 h and assayed for LNG and sex hormone binding globulin.

RESULTS

LNG concentrations peaked in plasma and in milk 1-4 h and 2-4 h after dosing, respectively. Concentrations in milk (M) paralleled those in plasma (P) but were consistently lower (mean M:P ratio 0.28). Estimated infant exposure to LNG is 1.6 microg on the day of dosing (1 microg in the first 8 h), 0.3 microg on the second day and 0.2 microg on the third day.

CONCLUSIONS

Nursing mothers may need EC. These results suggest that to limit infant exposure to the period of maximum LNG excretion in milk, mothers should discontinue nursing for at least 8 h, but not more than 24 h, after EC.

Health and growth of infants breastfed by Norplant contraceptive implants users: a six-year follow-up study

The objective of the study was to evaluate safety to infants whose mothers used Norplant levonorgestrel implants during breastfeeding. A nonrandomized clinical trial design was used. Participants were 220 and 222 healthy breastfed infants of mothers initiating use of Norplant or T-Cu IUD, respectively, at 55 days to 60 days postpartum. Infants were followed from birth through age 6 years. Breastfeeding pattern, infant growth, and disease events were recorded monthly in the first year, three-monthly in the second, and annually thereafter. Most mothers continued use of Norplant (96.4%) and T-Cu (94.1%) during lactation, and 2140 months of infant exposure to levonorgestrel were accumulated. Breastfeeding pattern and infants growth, from admission through age 6 years, were similar in both groups. In the first year, breastfed infants in the Norplant group had higher incidence rates (p < 0.05) of mild episodes of respiratory infections (adjusted RR 1.17, CI 1.08-1.27), skin conditions (adjusted RR 1.46, CI 1.20-1.79), and eye infections (unadjusted RR 1.49, CI 1.03-2.18) than the control group. Later on, a higher proportion of infants in the T-Cu group showed neurological conditions. Although breastfeeding patterns and infant growth is not affected by Norplant use during lactation, the effect on infants' health of steroidal contraception should be further evaluated.

Contraceptive implants and lactation

The safety and efficacy of four contraceptive implants, plant, Implanon, Nestorone and Elcometrine, have been evaluated during use in the postpartum period by lactating women. These implants provide highly effective contraceptive protection with no negative effect on breastfeeding or infant growth and development. Breastfeeding women initiating Norplant use in the second postpartum month experience significantly longer periods of amenorrhea than do untreated women or intrauterine device users. After weaning, the bleeding pattern is similar to that observed in non-nursing women. Norplant use does not affect bone turnover and density during lactation. Norplant and Implanon release orally active progestins while Nestorone and Elcometrine implants release an orally inactive progestin, which represents an advantage since the infant should be free of steroidal effects. The infant's daily intake of steroids (estimated from concentrations in maternal milk during the first month of use) range from 90 to 100 ng of levonorgestrel (Norplant), 75-120 ng of etonogestrel (Implanon), and 50 ng and 110 ng of Nestorone (Nestorone and Elcometrine implants, respectively). Nursing women needing contraception may use progestin-only implants when nonhormonal methods are not available or acceptable. Implants that deliver orally active steroids should only be used after 6 weeks postpartum to avoid transferring of steroids to the newborn.

Contraceptive efficacy and clinical performance of Nestorone implants in postpartum women

The objective of this study was to evaluate the contraceptive efficacy and clinical performance of a Nestorone subdermal implant (NES) in the postpartum period. NES (n = 100) and Copper T intrauterine device (T-Cu; n = 100) acceptors initiated contraception at 8 weeks postpartum and were followed at monthly intervals during the first year and at 3-month intervals thereafter. Pregnancy rates, breastfeeding performance, infant growth, bleeding pattern, and side effects were assessed. Blood and milk NES concentration were measured. No pregnancy occurred in 2195 and 2145 woman-months of NES implant and T-Cu use, respectively. No effect of NES on lactation and infant growth and no serious adverse events were observed. Lactational amenorrhea was significantly longer in NES users (353 +/- 20 days) than in T-Cu users (201 +/- 11 days). More NES users (55.8%) experienced prolonged bleedings than did T-Cu users (36.2%). Concentrations of NES in breast milk ranged between 54-135 pmol/liter. The Nestorone implant is a highly effective contraceptive, safe for breastfed infants because the steroid is inactive by the oral route.

Contraceptives for lactating women: a comparative trial of a progesterone-releasing vaginal ring and the copper T 380A IUD

From approximately one week before normal ovulation resumes, lactating women require protection against pregnancy by a contraceptive that is safe for both infant and mother in a multicenter one-year study, the natural hormone, progesterone, delivered vaginally by a sequence of four contraceptive rings designed for continuous use, was evaluated as a contraceptive for nursing mothers in comparison with the Copper T 380A IUD. Individual rings release in effective average dose of 10 mg day for a 3 month period. Evaluation included measures of lactational performance as well as of contraceptive efficacy and safety to mother and child. Nine participating clinics enrolled 802 ring users and 734 IUD acceptors between postpartum days 29 and 63. Life table analyses were performed with parallel decrements for ring and IUD subjects. Continuation in the study and analysis required that subjects not stop breastfeeding. The ring, with a one-year pregnancy rate of 1.5 per 100, did not differ significantly from the IUD with respect to contraceptive effectiveness (p > 0.05). More than half of the ring subjects were continuing at 6 months post admission and a quarter (23.5 per hundred) were still using the ring and breastfeeding one year after admission. Women with the IUD, however, had higher continuation rates (p < 0.001) at both time points. The largest single decrement for each method was that for weaning. Ring users had more complaints of vaginal problems but had fewer vaginal disorders on examination. At 12 months postpartum, 46 per 100 continuing ring users remained in amenorrhea. Lactation performance and the health and weight gain of the infants were similar among users of either regimen.

Post-partum contraception

The choice of a post-partum contraceptive method depends on many factors, including the need for a temporary versus a permanent method, the infant feeding choice and the extent to which informed consent is made prior to delivery. For maximum protection, the non-breast-feeding woman should be protected from the fourth week post-partum, even if that means using a temporary method, such as condoms or spermicides, until her method of choice is procured. Combined oestrogen/progestin methods should be avoided by all women for 2-3 weeks to avoid elevating the risk of thromboembolism. Preparations containing oestrogen should be avoided altogether during lactation because they have been associated with a reduction in milk production. POPs, implants and injectables are appropriate regardless of infant feeding choice. They can be administered immediately post-partum in bottle-feeding women, but should ideally be postponed for 6 weeks in breast-feeding women. It is best to insert IUDs within 10 minutes of delivery of the placenta, in order to minimize the risk of IUD expulsion. Insertion immediately after expulsion of the placenta requires special training, and expulsion rates are reduced with the insertion experience of the practitioner. Breast-feeding is not associated with an increase in IUD expulsion or uterine perforation, and it is associated with fewer removals for bleeding or pain. Tubal sterilization is safe, convenient and cost-effective when performed immediately after delivery, but it requires extensive counselling and fully informed consent prior to the onset of labour to avoid potential regret over post-partum tubal ligation. If the procedure is performed immediately, any effect on the establishment of lactation may be minimized. LAM is a method that can only be used by breast-feeding women. It may prove to be a useful way to time the commencement of a second, less temporary contraceptive method. Natural family planning methods require a period of abstinence for the establishment and identification of the new symptoms of fertility. When LAM is used during this interval, the need for abstinence may be reduced significantly for breast-feeding women. Breast-feeding provides health benefits for the woman and her infant, as well as the best possible nutrition for the baby. The International Planned Parenthood Federation (1990) (among others) recommends that, 'As far as is practicable, all women should be advised and encouraged to breastfeed fully'. The infant feeding decision affects the choice of a contraceptive method, and this is an important reason for the woman's physician to be interested in her infant feeding choice.

Progestin-only pill use and pill switching during breastfeeding

The opinions of 20 international experts in reproductive endocrinology and family planning service delivery were solicited concerning contraceptive pill use during breastfeeding and, in particular, to determine whether the experts felt that breastfeeding women who use progestin-only pills (POPs) should be advised to switch to combined estrogen-progestin pills (COCs) during lactation. The experts agreed that POPs can be used safely and effectively throughout the period of lactation and there is no need to switch to another contraceptive method or another type of pill. If, however, a woman wishes to switch to COCs while she is still breastfeeding, it is acceptable for her to do so after six months postpartum.