There is more than one reason for a woman becoming pregnant after her partner has had a vasectomy, but the main reason is not using an alternate birth control method for the first few months following the procedure. For a short time after a vasectomy a man will have a small reserve of viable sperm; this means she can still get your partner pregnant. Keep in mind that he may still have viable sperm for up to six months after your procedure, although this is not common.
A Second Cause for Pregnancy After Vasectomy
A second reason for a pregnancy after vasectomy is that the operation failed because the vas deferens grew back together. Pregnancy after vasectomy due to this reason is very rare; it is only one in every 2,000 procedures that this happens. When it does occur it is called recanalization.
The primary reason recanalization occurs and causes a pregnancy after vasectomy is that there are little pieces of debris from sperm, white blood cells, and scar tissue that allow cells in the vas deferens to grow through it and thus reconnect the place where the incision was made splitting the vas deferens.
What One Study Says About Pregnancy After Vasectomy
One study published in May 2004 in the medical journal Obstetrics and Gynecology which studied 540 women between the ages of 18 and 44 found that six of those women became pregnant 6 to 72 weeks after their husbands underwent a vasectomy. Three pregnancies happened within the first three months, and most likely occurred because the couple was not practicing an alternative method of birth control as advised by physicians. Two pregnancies happened twelve months after their husbands had their vasectomies and were thought to be because the procedure failed and the vas deferens grew back together.
What One Survey Says About Pregnancy After Vasectomy
The clinical research department at Family Health International in North Carolina surveyed 2,000 urologists by mail and one of the questions dealt with pregnancy after vasectomy and how often it occurred. A total of 586 of the urologists sent back completed surveys and 538 of them had performed vasectomies.
There were 177 pregnancies declared in the five years after the vasectomies were performed. Fifty-one percent were caused by the couple having unprotected sex within the danger zone after the vasectomy was performed. The other pregnancies were thought to be from the vas deferens growing back together and other less common reasons.
While pregnancy after vasectomy is uncommon it is not unheard of. Only three percent of men go to the follow-up appointments suggested by physicians at three and six months. If you have had a vasectomy and are concerned about your partner becoming pregnant it is advisable that you use an alternate method of birth control during the dangerous period, and that you go to the follow-up appointments to have your sperm counted so you know when you no longer have sperm in your semen.