What is thought to be a permanent contraceptive solution may actually be less effective at preventing pregnancy than less invasive methods, new research suggests.
Researchers at the University of California found that up to five percent of women who underwent tubal ligation, commonly known as the tying of the fallopian tubes, subsequently became pregnant.
Tubal ligation is considered irreversible and is the most common form of contraception used worldwide (more women choose it than oral contraceptives).
Most women who undergo the procedure, which involves cutting the fallopian tubes so that eggs cannot travel to and be fertilised by sperm, do so because they are already mothers and do not want to have more children, while many younger women choose to remain childless.
Previous estimates of pregnancies among women who have had their tubes tied have been around one percent, but a new study has found that post-tubal ligation pregnancies “may be considerably more common than many expect” — between three and five percent.
Tubal ligation, also known as having your tubes tied, was found to be less effective at preventing pregnancy than common reversible birth control methods, such as IUDs.
The researchers concluded that for women, especially younger ones, a reversible form of contraception, such as an intrauterine device (IUD) or an implant in the arm, might be more effective than the so-called “permanent” option.
The study, led by researchers at UC San Francisco, collected medical data from more than 31,000 women ages 15 to 44 who participated in the National Survey of Family Growth from 2002 to 2015.
Of that total, 4,184 reported having undergone the procedure, in which doctors clamp the fallopian tubes or cut them and remove them.
In four waves of data collection during that period, between 2.9 and 5.2 percent of women became pregnant despite undergoing the procedure.
In the most recent data set, from 2013 to 2015, nearly three percent of women became pregnant within the first year after undergoing surgery. Nearly nine percent of them became pregnant within ten years after the procedure.
Dr. Eleanor Bimla Schwarz, a UCSF internal medicine physician and author of the study, said: “For people who have chosen a ‘permanent’ method, finding out they’ve become pregnant can be very distressing. It turns out that, unfortunately, this is a fairly common experience.
‘This study shows that tubal surgery cannot be considered the best way to prevent pregnancy.
‘People who use a contraceptive implant in their arm or an IUD are less likely to get pregnant than those who have their tubes tied.’
An IUD releases hormones that prevent pregnancy more than 99 percent of the time and can remain in place for up to five years.
An implantable contraceptive method that is inserted into a person’s upper arm is also more than 99 percent effective and can remain in the arm for three years.
The team of researchers called for further research into the efficacy of the procedure, which around 700,000 women choose to undergo each year.
This is more than what many people who choose to take birth control pills realize, believing they are making a permanent family planning decision.
About 18 percent of women choose to have their tubes tied, according to to CDC dataWhile 14 percent of women take birth control pills, about 10 percent of women choose long-acting contraceptive methods, such as an IUD or an implant in the arm.
According to the study’s findings, 700,000 women opt for tubal ligation in a single year and 20,000 of them could become pregnant later on.
The UCSF findings were published in New England Journal of Medicine Evidence.
The researchers added that in the wake of the Supreme Court’s decision to overturn the federal right to abortion in Dobbs v Jackson and the domino effect of states enacting bans that followed, being informed about the best contraception options is paramount.
Dr Schwarz said: ‘Since the Dobbs decision, many more people are concerned about the impact pregnancy can have on their health and family life.
“This is especially true for patients with medical conditions such as diabetes and high blood pressure that can complicate pregnancy.”
Public interest in surgical sterilization increased after the Dobbs decision was issued three years ago, primarily among young people aged 18 to 30.
According to a 2024 report by public health researchers in Pittsburgh and Boston, the monthly rate of tubal ligations increased from 2.84 procedures per 100,000 women per month before the Dobbs Act. at 58.02 procedures per month for women after the decision was issued.
Dr Schwarz added: “For people who have chosen a ‘permanent’ method, finding out they’ve become pregnant can be very distressing. It turns out that, unfortunately, this is a fairly common experience.”