San Francisco — New research suggests that the rate of pregnancy following tubal sterilization may be higher than previously estimated. An analysis of national survey data reveals that 2.9% to 5.2% of women who had undergone tubal sterilization later reported becoming pregnant, according to a study led by Dr. Eleanor Schwarz of the University of California, San Francisco, and published in NEJM Evidence.
The study examined data from four waves of the National Survey of Family Growth (NSFG), covering the periods 2002, 2006-2010, 2011-2013, and 2013-2015. It found that the failure rate of tubal sterilization was 2.9% within one year of the procedure and increased to 8.4% by ten years.
Dr. Schwarz highlighted the importance of this information in the context of reduced access to abortion services following the Dobbs decision. “With the current limitations on pregnancy termination services, understanding the effectiveness of contraceptive methods is crucial,” she stated.
Dr. Schwarz and her team analyzed data on women aged 15-44, focusing on the time elapsed between tubal sterilization and subsequent pregnancy. The majority of these procedures were performed postpartum, and more than half of the women were under 35 at the time of surgery. Although most pregnancies were intrauterine, between 12.1% and 32.6% were ectopic.
The study found that while postpartum tubal sterilizations generally had lower failure rates compared to interval procedures, these differences did not persist when adjusted for multiple variables. Age was a significant predictor of pregnancy, with older women less likely to conceive after tubal sterilization.
Funding sources for the procedure did not affect the likelihood of subsequent pregnancy, nor did factors such as race/ethnicity, educational attainment, or metropolitan residency.
In an editorial accompanying the study, Drs. Julia Tasset and Maria Rodriguez from Oregon Health & Science University emphasized that this research updates clinical understanding of tubal sterilization effectiveness with modern laparoscopic techniques. They noted that the failure rates reported in this study are significantly higher than those from the 40-year-old CREST (Collaborative Review of Sterilization) study and exceed the typical failure rates of long-acting reversible contraceptives like intrauterine devices and subdermal implants.
Dr. Hyungjin Myra Kim from the University of Michigan praised the study’s design, particularly its effective use of existing survey data. “The researchers have skillfully utilized secondary data analysis to draw meaningful conclusions about tubal sterilization,” Kim noted.
However, the study has limitations. The NSFG relies on participant recall and does not differentiate between types of laparoscopic procedures or between hysteroscopic and laparoscopic methods, though effectiveness rates are reported to be similar. Additionally, the NSFG data may underreport abortions and does not capture all instances of assisted fertility treatments.
The findings underscore the need for women considering tubal sterilization to be fully informed about alternative long-term contraceptive options, such as hormonal intrauterine devices, arm implants, or vasectomy, which may offer higher efficacy.
