Perimenopause: pregnancy risks

During perimenopause, undesired pregnancies occur at ratios similar to or even higher than younger age groups, and almost half of these pregnancies will be terminated. (1) In the United States, roughly one-third of pregnancies occurring in the 40- to 45-year age cohort are unintended. (1) However, perimenopausal women may use contraception less consistently than younger women (2), possibly due to a lower perceived risk of pregnancy. Clinicians should continue to offer pregnancy prevention counseling and services to patients until they reach natural menopause if pregnancy is not desired, advise Amanda Black, MD, MPH, Alexandra Sherman, NP, and Taniqua Miller, MD, in Contraceptive Technology. (3)

Fertility at first gradually then rapidly declines with age due to diminishing oocyte quality and ovarian reserve with an associated increase in anovulatory cycles and luteal insufficiency. Evidence of luteal phase activity (ovulation) is seen in 87.9% of cycles up to 5 years before menopause and is still seen in 22.8% of cycles within 1 year of the final menstrual period. (4)

During the perimenopause, the chance of naturally occurring pregnancy is approximately 30% per year at ages 40–44 and decreases to 10% per year from ages 45–49. (5) Spontaneous pregnancy over the age of 50 is rare but people at this age are still potentially fertile during the perimenopause. (5) Thus if an individual is engaging in heterosexual intercourse and a pregnancy is not desired, an effective method of contraception should be used consistently. 

What are the Reproductive Outcomes if Pregnancy Occurs During Perimenopause?

Compared with younger women, pregnancies in older reproductive age women result in poorer obstetrical and maternal outcomes, warn Black, Sherman, and Miller. Compared to pregnant persons aged 25–29, risk of severe maternal mortality and morbidity increased 1.6 times at 40–44 years old, 2.0 times at 45–49 years old, and to 5.2 times at 50 years or more. (6)

Age itself is an independent risk factor for poorer reproductive outcomes. Further increased risk may be seen with advanced maternal age due to additional medical comorbidities such as diabetes, hypertension, and obesity. (7, 8)

In an ongoing pregnancy, there is an increase in maternal complications including gestational diabetes, placenta previa, gestational hypertension, severe pre-eclampsia, and placental abruption. (7,10, 9) The likelihood of cesarean section over the age of 40 years is two to three times higher than in those younger than age 25. (9) The risk of ectopic pregnancy and perinatal death also increases with age.

The risk of spontaneous abortion and chromosomal abnormalities increases markedly after the age of 40. (10) More than 50% of pregnancies between the ages of 40 and 44 years end in miscarriage, increasing to more than 90% over age 45. (11, 12, 13) The predicted odds of delivering a child at term with Trisomy 21 increases from 1:85 at age 40 to 1:35 at age 45. (13) The risks are even higher when considering aneuploidy. Conception after age 40 is associated with both an increased risk of early pregnancy loss as well intrauterine fetal death. (14)

Neonatal complications include increased risks of preterm delivery, low birth weight, intrauterine growth restriction, and perinatal mortality. (7, 8, 9, 10, 15) In the postpartum period, readmissions after birth are increased. (16) Advances in maternal and fetal monitoring allow most pregnancies in people older than 35 to progress without significant complications.

Contraception During the Later Reproductive Years

The actual risks of pregnancy should be addressed during any discussions about family planning and contraceptive options during the perimenopause. These risks must be balanced against the risks of continuing contraception, particularly risks of acute cardiovascular events, loss of bone mineral density, or breast cancer. In general, the risks of pregnancy outweigh the risks of contraception for most people.

The failure rates of any contraceptive method are lower over the age of 40 compared to younger individuals because overall fertility is lower in this age group. If there is a lower risk of pregnancy, methods with lower inherent efficacy may be suitable. Considerations include coital frequency, partner fertility, predictability of ovarian reserve, and the health risk posed by pregnancy.

No contraceptive method is contraindicated on the basis of age alone, (17) as there are no data to suggest that age itself is a risk factor for contraceptive-related complications. As such, contraceptives may be used up to age 55, the age at which 90% of women will have experienced the final menstrual period, so long as doing so is medically prudent. (18)

While the contraindications for contraceptive use in older persons mirror

younger users, medical conditions may develop with age that may preclude the use of certain methods, in particular estrogen-containing methods. Conditions to consider include hypertension, obesity, smoking, diabetes, migraine with aura, and cardiovascular disease. Other important aspects of the medical history include history of venous thromboembolism (VTE), malignancy, and medications.

References

1. Finer LB, Zolna MR. Declines in unintended pregnancy in the United States, 2008-2011. N Engl J Med. 2016;374:843-52.
2. Black A, Yang Q, Wu Wen S, Lalonde AB, Guilbert E, Fisher W. Contraceptive use among Canadian women of reproductive age: results of a national survey. J Obstet Gynaecol Can. 2009; 31:627-40.
3. Black A, Sherman A, Miller T. Contraception in the later reproductive years. In: Cason P, Cwiak C, Edelman A, et al. [eds.] Contraceptive technology. 22 nd edition. Burlington, MA: Jones-Bartlett Learning, 2023.
4. Santoro N. Using antimullerian hormone to predict fertility. JAMA. 2017;318:1333-4.
5. Avis NE, Brockwell S, Randolph JF, Jr., et al. Longitudinal changes in sexual functioning as women transition through menopause: results from the Study of Women’s Health Across the Nation. Menopause. 2009;16:442-52.
6. Lisonkova S, Potts J, Muraca GM, et al. Maternal age and severe maternal morbidity: A population-based retrospective cohort study. PLoS Med. 2017;14:e1002307.
7. Jacobsson B, Ladfors L, Milsom I. Advanced maternal age and adverse perinatal outcome. Obstet Gynecol. 2004;104:727-33.
8. Klemetti R, Gissler M, Sainio S, Hemminki E. At what age does the risk for adverse maternal and infant outcomes increase? Nationwide register-based study on first births in Finland in 2005-2014. Acta Obstet Gynecol Scand. 2016;95:1368-75/.
9. Joseph KS, Allen AC, Dodds L, Turner LA, Scott H, Liston R. The perinatal effects of delayed childbearing. Obstet Gynecol. 2005;105:1410-8.
10. Cleary-Goldman J, Malone FD, Vidaver J, et al. Impact of maternal age on obstetric outcome. Obstet Gynecol. 2005;105:983-90.
11. Nybo Andersen AM, Wohlfahrt J, Christens P, Olsen J, Melbye M. Maternal age and fetal loss: population based register linkage study. BMJ. 2000;320:1708-12.
12. Heffner LJ. Advanced maternal age–how old is too old? N Engl J Med. 2004;351:1927-9.
13. Morris JK, De Vigan C, Mutton DE, Alberman E. Risk of a Down syndrome live birth in women 45 years of age and older. Prenat Diagn. 2005;25:275-8.
14. Bouzaglou A, Aubenas I, Abbou H, et al. Pregnancy at 40 years old and above: obstetrical, fetal, and neonatal outcomes. Is age an independent risk factor for those complications? Front Med (Lausanne). 2020;7:208.
15. Olapeju B, Hong X, Wang G, et al. Birth outcomes across the spectrum of maternal age: dissecting aging effect versus confounding by social and medical determinants. BMC Pregnancy Childbirth. 2021;21(1):594.
16. Wen T, Overton EE, Sheen JJ, et al. Risk for postpartum readmissions and associated complications based on maternal age. J Matern Fetal Neonatal Med. 2021 May;34(9):1375-81.
17. Curtis KM, Tepper NK, Jatlaoui TC, et al. U.S. medical eligibility criteria for contraceptive use, 2016. MMWR Recomm Rep. 2016;65:1-103.
18. ESHRE Capri Workshop Group. Female contraception over 40. Hum Reprod Update. 2009; 15:599-612.