Vasectomy does not appear to be associated with reduced sexual activity, a large study from the United States has found.

The study authors used the National Survey of Family Growth (NSFG) dataset comprising 7,643 women and 4,928 men. The NSFG is a probability sample of the US population aged 15-45. One member per household was randomly selected from men over 25 who had been sexually active, and likewise women between the ages of 25 and 45.

Men were asked: ‘Have you ever had a vasectomy or any other operation that makes it impossible for you to father a child?’ Women were asked the same question about their partner.

Outcome measures included: the number of times the individual had had sexual intercourse in the previous four weeks: never, less than once a week, or one or more times a week. Further analysis was carried out using logistic regression to adjust for demographic, socioeconomic, health and reproductive factors known to influence the decision to have a vasectomy and sexual function.

There were 5,838 men aged 25-45 who met the study inclusion criteria, of whom 353 had undergone a vasectomy.

The average sexual frequency was 5.9 times a month for men who had had a vasectomy and 4.9 times in non-vasectomised men (P = 0.0004). Only 6% of vasectomised men reported not having sex in the previous month, compared with 15% of non-vasectomised men (P = 0.0062).

Two-thirds (66%) of vasectomised men had sexual intercourse one or more times a week compared with just over half (55%) of non-vasectomised men (P = 0.0186).

After adjusting for age, marital status, education, self-reported health, BMI, number of children and income level, vasectomised men had 81% higher odds of having sexual intercourse one or more times a week compared with non-vasectomised men (95% CI: 6-210%; P = 0.030).

For women whose partners had had a vasectomy, average sexual frequency was 6.3 times a month, compared with 6.0 for women whose partners were not vasectomised (P = 0.1341). After adjusting for other factors, women with vasectomised partners had 46% higher odds (95% CI: 5-103%) of having sexual intercourse one or more times a week compared with those with non-vasectomised partners (P = 0.024).

The study suggests not only that vasectomy is not associated with reduced sexual function, but that the converse may be true in some cases. The authors speculate that the apparent higher frequency of sexual intercourse in the vasectomised group might possibly be explained by: decreased anxiety about unplanned pregnancy, a desire to compensate for perceived demasculinisation or that those men who opted for vasectomy were a more sexually active subset before the procedure and continued to be afterwards.

This study might help to encourage more men to consider vasectomy as a long-lasting method of contraception.

Dr Richard Ma