Pregnancy is possible with only one ovary. The human reproductive system adapts remarkably, allowing the remaining ovary to often take over the function of the missing one. Individuals with a single ovary, whether from birth or following a surgical procedure (unilateral oophorectomy), still possess the components necessary for conception. Although the total potential egg count is reduced, the remaining organ continues to produce the hormones and eggs required for a regular menstrual cycle and ovulation.
How the Remaining Ovary Compensates
The body initiates compensatory function in the remaining ovary after the removal of its counterpart. The surviving ovary often increases in size, a phenomenon called compensatory hypertrophy, as it adjusts to meet reproductive needs. This enlargement is accompanied by increased activity in the recruitment and maturation of ovarian follicles.
This heightened activity is stimulated by the pituitary gland, which releases higher levels of Follicle-Stimulating Hormone (FSH). The surge in FSH drives the remaining ovary to produce a number of follicles and eggs similar to what two ovaries would normally yield combined. This hormonal adjustment helps maintain the regularity of the menstrual cycle and the potential for monthly ovulation.
The remaining fallopian tube also adapts to the anatomical change. Even if the ovary and tube on the same side were removed, the egg released from the remaining ovary can still be picked up by the tube on the opposite side. This movement, known as transperitoneal ovum migration, involves the egg traveling across the pelvic cavity to be captured by the fimbriae of the contralateral tube. This mechanism ensures that successful ovulation provides an opportunity for fertilization and implantation.
Key Factors Affecting Conception Success
While the body compensates, several factors independent of the single ovary influence conception chances. Age remains the most significant variable, as the quality of the remaining eggs naturally declines over time, particularly after the mid-thirties. The health of the remaining ovary and fallopian tube is also important for successful natural pregnancy.
The underlying reason the first ovary was lost is a major consideration, as the original condition may still affect the remaining reproductive organs. If the oophorectomy was performed due to severe endometriosis, pelvic inflammatory disease, or a complicated ectopic pregnancy, the remaining fallopian tube may have scarring or damage. Obstruction or functional impairment in the remaining tube could prevent the sperm and egg from meeting, even if the single ovary is ovulating effectively.
Medical history related to conditions like Polycystic Ovary Syndrome (PCOS) or a family history of early menopause can influence the remaining ovarian reserve and function. Women with a single ovary who have a healthy remaining tube and no other complicating health factors often have conception rates comparable to those with two ovaries. The presence of these co-existing conditions, however, can significantly lower the chances of natural conception.
When to Seek Medical Guidance
Individuals with a single ovary should monitor their fertility, though the standard timeline for seeking medical guidance remains the same. For those under 35, a fertility evaluation is recommended if conception has not occurred after one year of regular, unprotected intercourse. This timeline shortens to six months of trying for those aged 35 or older, due to the faster decline in egg quality.
If the reason for the single ovary was a condition known to affect fertility, such as severe endometriosis or pelvic inflammatory disease, consult a specialist immediately upon deciding to try for a pregnancy. Initial evaluations involve hormone testing, such as Anti-Müllerian Hormone (AMH) and Follicle-Stimulating Hormone (FSH) levels, to assess the ovarian reserve. An ultrasound or specialized X-ray procedure can also be performed to check that the remaining fallopian tube is open and functional.
If natural conception is delayed, assisted reproductive technologies (ART) remain a viable and successful option. While a single ovary may yield fewer eggs during an in vitro fertilization (IVF) cycle compared to two, studies show that the overall chance of achieving a live birth through ART is not reduced. A fertility specialist can create a personalized plan to optimize the chances of pregnancy using the remaining ovary’s function.