A Cochrane review (abstract [Abstract], review [Abstract]) included 11 studies involving a total of 1 482 participants. 4 trials examined combined oral contraceptives (COCs), 3 studied a levonorgestrel-releasing intrauterine system (LNG-IUS), 2 studied progestin-only pills (POPs) and 2 of the etonogestrel-releasing implant. Most trials did not report significant differences between the study arms in breastfeeding duration, breast milk composition, or infant growth. The few exceptions were seen mainly in older studies with limited reporting.For breastfeeding duration, 2 of 8 trials indicated a negative effect on lactation: A COC study reported a negative effect on lactation duration compared to placebo but did not quantify results. Another trial showed a lower percentage of the LNG-IUS group breastfeeding at 75 days versus the nonhormonal IUD group (reported P < 0.05) but no significant difference at one year.For breast milk volume, 2 older studies indicated lower volume for the COC group versus the placebo group. One trial did not quantify results. The other showed lower means (mL) for the COC group, e.g. at 16 weeks (MD -24.00, 95% CI -34.53 to -13.47) and at 24 weeks (MD -24.90, 95% CI -36.01 to -13.79). Another 4 trials did not report any significant difference between the study groups in milk volume or composition with two POPs, a COC, or the etonogestrel implant.
A systematic review 7 including 13 studies assessed breastfeeding and infant health among breastfeeding women using combined hormonal contraception (CHC) compared to nonusers. None of the studies found an effect on infant weight gain when COCs were started after 6 weeks postpartum, and no studies found an effect on other infant health outcomes regardless of time of COC initiation.
An RCT 8 studied whether immediate postpartum insertion (within 5 days) of levonorgestrel contraceptive implants was associated with a difference in infant growth from birth to 6 months compared with delayed (6 to 8 weeks postpartum) insertion. The mean change in infant weight from birth to 6 months was similar between groups: 4632 g in the immediate group (n=96) and 4407 g in the delayed group (n=87) (p=.26). Among the 97 women who had not experienced lactogenesis prior to randomization, the median time to onset of lactogenesis did not differ significantly between the immediate and delayed groups (65 h versus 63 h; p=.84). Similar proportions of women in the immediate and delayed groups reported exclusive breastfeeding at 3 months (74% versus 71%; p=.74) and 6 months (48% versus 52%; p=.58).
A noninferiority trial 9 randomized 95 participants to etonogestrel implant insertion at 0 to 2 hours (delivery room) vs 24 to 48 hours (delayed) postdelivery. There was no difference in time to lactogenesis stage II (mean difference -9 hours; 95% CI -27 to 10), or in ongoing breastfeeding rates of any/exclusive breastfeeding over the first postpartum year.
In a prospective study 4 in Brazil women (n=40, age 18 - 44) who delivered in the hospital initiated on postpartum day 42 the contraceptive method of their choice (COC, LNG-IUS, or etonogestrel-releasing implant, or Cu-IUD as a reference group). Deuterium (D2O; 0.5 g/kg mother's weight) was ingested by mothers on postpartum days 42, 52, and 63 as a marker of total body fluid. Infants' milk intake from 42 to 63 postpartum days was assessed by measurement of D2O levels in infants' saliva and infant growth by measuring their body weight, height, and tibia length. Infant mean milk intake, mean growth increase, mean number of breastfeeding episodes, daily wet diaper changes. The incidence of full breastfeeding and breastfeeding continuation was similar between the groups, and there were no significant differences in infant growth.
Another prospective study 5 assessed the effects of an etonogestrel-releasing implant (Implanon) and a nonmedicated intrauterine device (IUD) on lactation in breastfeeding women and on the growth of their breastfed infants over a 3-year period in Thailand. Healthy lactating women (28-56 days postpartum) chose either the implant (n=42) or the IUD (n=38). Total duration of breastfeeding coinciding with the mothers' treatment was 421.0 and 423.4 days in the Implanon and IUD groups, respectively. There were no differences between the infant groups in terms of body length, biparietal head circumference and body weight. No abnormalities were reported in psychomotor development or during physical examination. No treatment-related side effects were observed in either group.
A noninferiority RCT 6 examined the effect of immediate (n=132) vs delayed (4-12 weeks, n=127) postpartum levonorgestrel intrauterine device (LNG-IUD) insertion on breast-feeding outcomes. Report of any breast-feeding at 8 weeks in the immediate group (79%; 95% CI, 70 to 86%) was noninferior to that of the delayed group (84%; 95% CI, 76 to 91%). The 5% difference in breast-feeding continuation fell within the noninferiority margin (95% Cl, -5.6 to 15%). A total of 24 IUD expulsions occurred in the immediate group compared to 2 in the delayed group (19% vs 2%, P < .001). No IUD perforations occurred in either group.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment and blinding in half of the studies).
Primary/Secondary Keywords