A new study has uncovered a surprising association, finding that the surgical removal of the appendix or tonsils in younger age may increase a woman’s chance of pregnancy.

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Women who underwent a tonsillectomy or appendectomy when younger were found to have higher pregnancy rates in a new study.

Study co-author Sami Shimi, clinical senior lecturer in the School of Medicine at the University of Dundee, United Kingdom, and colleagues say their findings – published in Fertility and Sterility – should ease concerns that such procedures may reduce a woman’s fertility.

The surgical removal of the tonsils, known as a tonsillectomy, is normally carried out as a result of frequent infection or inflammation of the tonsils (tonsillitis) or sleep-disordered breathing.

Surgical removal of the appendix, called an appendectomy, is normally the first-line treatment when the organ becomes infected or swollen – a condition known as appendicitis.

Both surgical procedures are common in the United States; studies suggest 1 in every 2,000 people have an appendectomy at some point in their lifetime, while more than 500,000 tonsillectomies take place in the U.S. each year, mostly among children.

According to Shimi, it was once a popular notion that young women who have an appendectomy may be less likely to become pregnant later in life.

But in 2012, he and his team conducted a study that revealed appendectomy may actually have the opposite effect for fertility.

This latest study builds on those findings, revealing that both tonsillectomy and appendectomy may improve a woman’s chance of pregnancy.

“Our first study produced such a surprising result – that women who had had their appendix removed actually appeared more likely to become pregnant – that we wanted to look at a wider group to establish whether this was really related to the removal of the appendix, which if left can be a cause of inflammation,” says Shimi.

To reach their findings, the team analyzed the medical records of 54,675 women who had received an appendectomy only, 112,607 women who had a tonsillectomy only, and 10,340 women who had both surgical procedures.

All women were from the U.K. and had undergone the procedures between 1987-2012.

The researchers analyzed the pregnancy rates among each group of women following their surgical procedures, and these were compared with those of 355,244 age-matched women from the general population who had not had a tonsillectomy or appendectomy.

Compared with women in the general population, women who had an appendectomy, tonsillectomy, or both had higher pregnancy rates, the team found.

While the pregnancy rate of women in the general population was 43.7 percent, the pregnancy rate of women who had an appendectomy or tonsillectomy was 54.4 percent and 53.4 percent, respectively. The pregnancy rate was even higher for women who had both procedures, at 59.7 percent.

What is more, women who underwent one or both of the surgical procedures were more likely to become pregnant sooner than those who had not had either procedure.

The researchers stress that their results do not suggest that women should undergo a tonsillectomy or appendectomy in order to increase their chances of becoming pregnant.

However, they do believe the results should alleviate young women’s concerns that an appendectomy may affect future fertility.

“[…] once again the results have been surprising. We have found that women who have had an appendectomy or tonsillectomy, or even more particularly both, are more likely to become pregnant, and sooner than the rest of the general population.

This scientifically challenges the myth of the effect of appendectomy on fertility. What we have to establish now is exactly why that is the case.”

Sami Shimi

The researchers say it is possible there is a biological explanation for why appendectomy and/or tonsillectomy appears to improve women’s fertility, but they believe a behavioral explanation is more plausible.

Read about a study that suggests most fertility apps are unlikely to help plan or prevent pregnancy.