TThis record contains information specific to levonorgestrel used alone. Those with an interest in a combination oral contraceptive should consult the record entitled, "Contraceptives, Oral, Combined."
Although nonhormonal methods are preferred during breastfeeding, progestin-only contraceptives such as levonorgestrel are considered the hormonal contraceptives of choice during lactation. Fair quality evidence indicates that levonorgestrel does not adversely affect the composition of milk, the growth and development of the infant or the milk supply. Some evidence indicates that progestin-only contraceptives may offer protection against bone mineral density loss during lactation, or at least not exacerbate it.
Based on the available evidence, expert opinion in the United States holds that the advantages of using progestin-only contraceptive products generally outweigh the theoretical or proven risks before 4 weeks postpartum. However, is prudent to give it no sooner than 3 days postpartum when lactation is established. The levonorgestrel IUD (Myrena) is recommended to be inserted at least 6 weeks postpartum and in some cases up to 12 weeks postpartum when uterine involution is complete. However, the American College of Obstetrics and Gynecology considers earlier insertion to be appropriate based on expert opinion. Two small, randomized studies on this point differed in their outcomes. One found that early insertion did not adversely affect breastfeeding, and the other found that immediate IUD insertion markedly reduced the breastfeeding rate at 6 months postpartum.
Use of 2 doses of 0.75 mg of levonorgestrel 12 hours apart for postcoital contraception has not been studied, but data from a study on a single 1.5 mg dose indicate that nursing can be resumed 8 hours after a large dose. Resumption of breastfeeding 3 to 4 hours after the dose may be acceptable.
Levonorgestrel is a synthetic progestin that is the active isomer of the racemate norgestrel. It is considered to be twice as potent on a weight basis as the racemic mixture. Norplant is a subdermal implant that releases levonorgestrel at a rate of about 85 mcg daily initially, dropping to about 50 mcg daily at 9 months. Norplant-2 releases levonorgestrel at a rate of about 50 mcg daily. Neither of the Norplant products are available in the United States at the time of this revision.
Maternal Levels, Oral.
Fifteen women who were fully breastfeeding and 8 weeks postpartum were given oral levonorgestrel either alone in a dose of 30 mcg daily or in an estrogen-containing oral contraceptive in a dose of 150 mcg or 250 mcg daily. Five women received each dose for 10 days before breastmilk sample collection. With the 30 mcg dose, the drug was undetectable in all of the women in prenursing milk (<0.05 mcg/L) or postnursing milk (<0.1 mcg/L) at 3 to 23 hours after the dose. With the 150 mcg dose, the highest levels in milk were found 3 hours after the dose with foremilk and hindmilk levels of 0.34 and 0.54 mcg/L, respectively; levels decreased to 0.11 and 0.17 mcg/L, respectively, at 23 hours after the dose. With the 250 mcg dose, the highest levels in milk were found 3 hours after the dose with foremilk and hindmilk levels of 0.51 and 1.05 mcg/L, respectively; levels decreased to 0.22 and 0.38 mcg/L, respectively, at 23 hours after the dose. The authors estimated that fully breastfed infants would receive 0.4 to 0.5 mcg daily in breastmilk, or about 0.1% of the total (not weight-adjusted) maternal dose.
Two women with well-established lactation (exact time postpartum not stated) were given an oral contraceptive containing 150 mcg of levonorgestrel daily. Each had breastmilk levels measured on 2 occasions 10 to 12 hours after a dose between days 6 and 20 of use. The average of their levonorgestrel milk levels was 0.18 mcg/L (range 0.135 to 0.223 mcg/L).
Milk levonorgestrel levels were measured in 4 women after daily ingestion of oral levonorgestrel 50 or 150 mcg started after 3 months postpartum. Peak milk levonorgestrel levels occurred between 1 and 3 hours and were in the ranges of 0.06 to 0.2 mcg/L after the 50 mcg dose and 0.35 to 0.45 mcg/L after the 150 mcg dose. After the 50 mcg dose, milk levels dropped to undetectable (<0.05 mcg/L) by 4 hours after the dose. After the 150 mcg dose, milk levels dropped to about 0.35 mcg/L at 4 hours after the dose and remained there for the next 2 hours.
At 6 to 20 weeks postpartum, 10 women received singletabletscontaining 30 mcg of levonorgestrel and another 15 women received a singletabletof a combination oral contraceptive containing 250 mcg of levonorgestrel. At 2 to 2.5 hours after the dose, a foremilk sample was taken. The mothers breastfed their infants and then a hindmilk sample was taken. The 2 samples were pooled for assay. After the 30 mcg dose, milk levels averaged 0.05 mcg/L (range 0.03 to 0.076 mcg/L); after the 250 mcg dose, milk levels averaged 0.64 mcg/L (range 0.3 to 1.3 mcg/L).
Twelve breastfeeding women averaging 11.1 weeks postpartum (range 6 and 12 weeks) received a single dose of 1.5 mg of levonorgestrel orally. Blood and milk samples were obtained over the next 72 hours. Peak milk levels of levonorgestrel occurred 3.9 hours after the dose; milk levels fell with a mean half-life in milk of 26 hours. The mean concentration in milk was 1.7 mcg/L during the first day, 0.4 mcg/L the second day and 0.2 mcg/L on the third day after the dose. The authors estimated that a fully breastfed infant would receive 1.6 mcg of levonorgestrel in the first 24 hours, 0.3 mcg in the second 24 hours, and 0.2 mcg in the third 24 hours after the dose.
Maternal Levels, Inplant.
One hundred women who received Norplant implants at an average of day 55 postpartum were compared to 100 women receiving a postpartum nonhormonal IUD. Milk levonorgestrel levels were measured at various times after insertion. During days 1 to 4 postinsertion, average milk levels were 0.079 mcg/L (n = 5); during days 9 to 14, average levels were 0.128 mcg/L (n = 22); during days 16 to 22, average levels were 0.163 mcg/L (n = 3); and during days 34 to 40, average levels were 0.116 mcg/L (n = 21). The authors estimated that a fully breastfed infant would receive a levonorgestrel dosage of 15 to 18 ng/kg daily in breastmilk during this time period.
A study compared women who received Norplant-2 (n = 14), an IUD that released 20 mcg levonorgestrel daily (n = 14) or oraltabletscontaining 30 mcg of levonorgestrel (n = 10) at 4 to 6 weeks postpartum. Pooled fore- and hindmilk samples were measured several times on the first day of drug use and periodically thereafter until day 28. Norplant-2 users had milk levels that reached an average of 0.067 mcg/L by day 2 and maintained those levels throughout the 28 days. IUD users had milk levels that reached an average of 0.046 mcg/L by day 2 and maintained those levels throughout the 28 days. Oraltabletusers had 2-hour peak milk levels that averaged 0.05 mcg/L throughout the 28 days.
Maternal Levels, IUD.
Ten women had IUDs that released either 10 mg or 30 mcg of levonorgestrel daily placed at 6 weeks postpartum. Milk was analyzed for levonorgestrel at various times over a 12-month period. All milk levels were less than 0.1 mcg/L, regardless of the dose that the mother was receiving.
Infant Levels, Oral.
Two 8-week old infants whose mothers were taking a combination oral contraceptive containing 250 mcg of levonorgestrel had plasma levels measured 5 hours after the maternal dose and 2 hours after nursing (i.e., nursed at the time of peak milk level). Plasma levels were 0.058 and 0.115 mcg/L in the 2 infants. A third infant whose mother was taking 30 mcg daily had undetectable (<0.005 mcg/L) in its plasma. The authors concluded that these results indicate that the infants are able to metabolize levonorgestrel and that no accumulation occurs in infant plasma.
At 6 to 20 weeks postpartum, 10 women received singletabletscontaining 30 mcg of levonorgestrel and another 15 women received a singletabletof a combination oral contraceptive containing 250 mcg of levonorgestrel. At 2 to 2.5 hours after the dose, the mothers breastfed their infants; infant serum samples were taken 1.5 to 2 hours later at about 4 hours after the maternal dose. Infant serum levels after the 30 and 250 mcg doses averaged 0.019 and 0.078 mcg/L, respectively. These levels were 2% and 1%, respectively, of peak maternal serum levels drawn at 2 to 2.5 hours after the dose.
Thirty mothers received 30 mcg oral levonorgestreltabletsdaily for 5 weeks. Ten began at 4 weeks postpartum, 10 began at 12 weeks postpartum and 10 began at 24 weeks postpartum. Because of assay and serum sample size limitations, serum samples were obtained from some of the breastfed infants during the first and fifth weeks of maternal therapy as representative of the entire group. Based on infant serum levels, the authors concluded that absorption of the drug was not great until 12 weeks postpartum and metabolism was not well developed until 24 weeks postpartum. The unusual and incomplete blood sampling scheme casts some doubt on the results of this study.
Infant Levels, Implant.
Forty-two women received Norplant implants between days 30 and 40 postpartum. The women breastfed for 1 year and donated 1 blood sample from herself and her infant once during the year. Infant serum levels averaged 1.5 mcg/L during the first month postpartum (n = 10); 3.95 mcg/L during the third month postpartum (n = 3); 4.2 mcg/L during the sixth month postpartum (n = 12); 2.5 mcg/L during the ninth month postpartum (n = 8); and, 3.6 mcg/L during the twelfth month postpartum (n = 11). Overall, the infants' serum levonorgestrel levels averaged 9.9% (range 4.9 to 12.6%) of simultaneous maternal serum levels.
A study compared women who received levonorgestrel as a contraceptive via Norplant-2 (n = 14), an IUD that released 20 mcg daily (n = 14) or oraltabletscontaining 30 mcg of levonorgestrel (n = 10) at 4 to 6 weeks postpartum. The serum levels of infants averaged 0.046 mcg/L and 0.03 mcg/L in infants whose mothers used Norplant-2 and the IUD, respectively. Infants whose mothers used oral levonorgestrel had peak serum levels (i.e., 2-hour postnursing and 4 hours after maternal ingestion) serum levels of 0.02 mcg/L. Infant serum levels averaged 2.9 to 4.6%, 6.7% and 2.2% of maternal serum levels for Norplant-2, the IUD and oraltablets, respectively.
Effects in Breastfed Infants:
Numerous studies have found no systematic differences in growth, development or illness rates between the infants of mothers who received Norplant as a contraceptive and those of other mothers receiving either no contraception or nonhormonal contraception. One study found serum thyroid stimulating hormone levels to be lower in the infants exposed to levonorgestrel than in control infants.
Oral and Implant.
A nonrandomized trial compared 250 breastfed infants whose mothers received 30 mcg daily of oral levonorgestrel initiated 7 days postpartum to 250 infants whose mothers received nonhormonal contraception. No differences in height and weight gain were seen during the 9-month study period between the 2 groups.
Ten women received Norplant-2 beginning at 4 weeks postpartum. Mothers collected 4-hour urine samples daily from weeks 4 to 11 postpartum from their infants. Urine samples were analyzed for follicle-stimulating hormone, luteinizing hormone and testosterone. No difference was found in these levels when compared to those of infants whose mothers were taking either no contraception or an oral progestin-only contraceptive containing 30 mcg of levonorgestrel.
Multicenter, nonrandomized studies followed infants whose mothers received levonorgestrel contraception during breastfeeding, either as oraltabletsof 37.5 mcg daily (n = 246) or as Norplant (n = 453). No adverse effects on infant growth through the first year were found in comparison to standard measurements. In a continuation study, infants from these studies who were exposed to levonorgestrel via Norplant (total n = 220) were followed up to 6 years of age. Infants were fully breastfed for an average of 7.8 months and were breastfed at least once daily for an average of 16.5 months. No differences in growth, diseases, surgery or hospitalizations were found from years 2 though 6 between infants whose mothers used levonorgestrel implants or Copper T IUD. An increase in skin conditions occurred in the levonorgestrel group and an increase in urogenital conditions occurred in the Copper T group.
In a cohort study of 71 women who took levonorgestrel as a postcoital contraceptive found no obvious decrease in milk supply after the drug was used according to maternal reports 75% of mothers re-initiated breastfeeding before 8 hours after the dose. None noticed any adverse effect in their infants.
IUDs that released levonorgestrel were inserted 6 weeks after delivery. IUDs released 10 mcg per day (n = 30) or 30 mcg per day (n = 40); copper-releasing IUDs (n = 40) were used as controls. No differences were seen in infant height, weight, development, respiratory infections or blood chemistries up to 12 months of age between the levonorgestrel and copper IUD groups.
Three hundred twenty lactating women were randomized to either an IUD containing levonorgestrel (Mirena; n =163) or the copper-containing IUD Cu T380A group (n =157). Follow-up of infants for 1 year found no differences in growth and development or in duration of breastfeeding.
Possible Effects on Lactation:
Numerous studies of varying size and quality have found that the use of levonorgestrel implants (Norplant or Norplant-2) as a contraceptive beginning at 7 days postpartum or later either has no clinically important negative effect on the quality of breastmilk and results in either no effect or an increase in the milk supply and duration of lactation.
In a nonrandomized study, 100 women who received Norplant implants at an average of day 55 postpartum were compared to 100 women receiving a postpartum IUD. No differences were found between the control and Norplant groups in the number of women nursing at days 10 and 20 and months 1 to 12 postinsertion except a slight decrease in the number of mothers using Norplant who were exclusively breastfeeding at 12 months. No difference since the time of weaning was noted between the groups.
IUDs releasing levonorgestrel were inserted 6 weeks after delivery. IUDs released 10 mcg per day (n = 30) or 30 mcg per day (n = 40); copper-releasing IUDs (n = 40) were used as controls. The rate of breastfeeding discontinuation was higher with the levonorgestrel groups than in the copper IUD group at 75 days, but not at other times.
In a nonrandomized, nonblinded study comparing women who were breastfeeding at discharge, 102 postpartum women received depot medroxyprogesterone acetate (dosage not stated) in the early postpartum period (average 51.9 hours postpartum; range 6.25 to 132 hours), 181 received another progestin-only contraceptive and 138 used nonhormonal contraception. No differences in breastfeeding rates were seen at 2 and 6 weeks, but women receiving any hormonal contraceptive were breastfeeding at a lower rate (72.1% vs 77.6%) at 4 weeks postpartum. The authors concluded that progestin-only contraception initiated in the early postpartum period had no adverse effects on breastfeeding rates.
In a small prospective study, forty-six women were randomized to have an IUD containing levonorgestrel (Mirena) inserted either within 10 minutes after placental delivery (n = 15), between 10 minutes and 48 hours after placental delivery (n = 15), or after 6 weeks postpartum (n = 16). At 6 months postpartum, no statistical difference in the rates of continued breastfeeding (extent not stated) was found among the groups.
Women who gave birth were offered contraception with a levonorgestrel-containing IUD and randomized to have the IUD placed immediately following delivery (n = 46) or at 6 to 8 weeks postpartum (n = 50). Women randomized to later IUD insertion were more likely to be nursing at 6 months postpartum (24% vs 6%) and tended to have a longer median duration of exclusive breastfeeding.
Among a cohort study of 71 women who took levonorgestrel as a postcoital contraceptive during nursing, none reported any obvious decrease in milk supply after the drug was used.
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Contraceptives, Oral, Synthetic
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