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#320 Oh Baby: Combined oral contraceptives during breastfeeding


CLINICAL QUESTION
Do combined oral contraceptives (COCs) affect breastfeeding or infant outcomes?

BOTTOM LINE
Trials are older (>35 years), small (<300 mom/infants) and highly unreliable. If results are real, COCs may lower infant growth (by~240g) and rates of exclusive breastfeeding (81% versus 92%) compared to placebo at 90 days. Progestin-only pill (POP) evidence is inconsistent/unreliable. If results are real, infant growth is not different compared to placebo. If early postpartum contraception is desired, guidelines recommend progestin-only methods due to increased venous thromboembolism risk.


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EVIDENCE
  • Randomized controlled trials (RCTs) from two systematic reviews.1,2 Oral contraceptives started 2-6 weeks postpartum. Results statistically different unless indicated.
  • COC versus placebo:
    • Infant weight:
      • 182 women, ethinyl estradiol 30mcg/levonorgestrel 0.15mg:3
        • At 91 days postpartum: 6011g versus 6250g (placebo).
      • 50 women, mestranol 80mcg with progestin:4
        • Between weeks 2-5 postpartum: Weight gain ~7oz less versus placebo, statistics not reported.
    • Exclusive breastfeeding:
      • At 91 days:3 81% versus 92% (placebo).
    • Supplemental formula:
      • At 91 days:3 Proportion supplementing: 18% versus 8% (placebo), not statistically different.
      • At 5 weeks:4 ~710 versus 190 supplemental calories/week (placebo), statistics not reported.
  • POP versus placebo:
    • Started ≤6 weeks postpartum: Two low-quality RCTs (20 and 400 women).5,6
      • Infant growth: No difference.2
  • COC versus POP:
    • Largest RCT (171 women) comparing ethinyl estradiol 30mcg/levonorgestrel 150mcg versus levonorgestrel 150mcg over 6-24 weeks postpartum:7
      • No difference: Infant weight or supplementation.
      • Milk volume: Decreased 42% COC vs 12%.
    • Results consistent with other RCT (127 women);8
      • No difference: Breastfeeding or adverse effects at 6 months.
  • Limitations: Old trials (>35 years);3-5,7 incomplete reporting;3,4,7 underpowered;8 high drop-outs;7,8 unclear randomization;3 some formulations/doses no longer used.4,9
  • COC adverse effects on mother/child pairs from non-RCTs:
    • 48 pair: No difference in growth/intellectual development versus control, ≤8 years.9
    • 103 versus 227 pairs (placebo/intrauterine device): No difference in infant breast/genital changes at 1 year.10
Context
  • Guidelines recommend:
    • Progestin-only contraception during early postpartum period.11,12
    • Against COC within first 4-6 weeks postpartum while breastfeeding due to venous thromboembolism risk.12,13
      • Early postpartum risk is 15-35 times non-pregnant,12,14 returning to baseline at 6-12 weeks.14

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Author(s):

  • Allison Paige MD CCFP
  • Jennifer Potter MD CCFP
  • Samantha Moe PharmD

1. Tepper NK, Phillips SJ, Kapp N, et al Contraception. 2016; 3(94): 262-74.

2. Lopez LM, Grey TW, Stuebe AM, et al. Cochrane Database Syst Rev. 2015; 3:CD003988.

3. Diaz S, Peralta O, Juez G, et al. Contraception. 1983; 27:1:1-11.

4. Miller GH, Hughes LR. Obstet Gynecol. 1970; 35(1):44-50.

5. Giner Velazquez, Cortes Gallegos V, Sotelo Lopez A, et al. Ginecol Obstet Mex 1976; 40(237):31-9.

6. Dutta DK, Dutta I. J Indian Med Assoc 2013; 111(8):553-5.

7. Tankeyoon M, Dusitsin N, Chalapati, S, et al. Contraception. 1984; 30(6):505-22.

8. Espey E, Ogburn T, Leeman L et al. Obstet Gynecol. 2012; 119(1):5-13.

9. Nilsson S, Mellbin T, Hofvander Y, et al. Contraception. 1986; 34(5):443-57.

10. Croxatto HB, Diaz S, Peralta O, et al. Contraception. 1983: 27(1):13-25.

11. Black A, Guilbert E, Costescu D, et al. JOGC. 2016; 38(3):279-300.

12. The Faculty of Sexual and Reproductive Healthcare. https://www.fsrh.org/standards-and-guidance/documents/contraception-after-pregnancy-guideline-january-2017/. Accessed June 29, 2022.

13. Black A, Guilbert E, Costescu D, et al. JOGC 2017; 39(4): 229-268.

14. Thrombosis Canada. https://thrombosiscanada.ca/wp-uploads/uploads/2021/11/42.-Pregnancy-Diagnosis-of-DVT-and-PE_14Sept2021.pdf. Accessed June 29, 2022.

Authors do not have any conflicts of interest to declare.