Getting pregnant with only one ovary is possible. The surgical removal of one ovary is medically termed a unilateral oophorectomy, and the remaining ovary is typically capable of sustaining normal reproductive function. The single remaining ovary often compensates for the loss of its partner, continuing to release an egg each cycle. While the overall ovarian reserve—the total number of eggs—is reduced, the ability to ovulate and conceive naturally remains, and most women maintain a regular menstrual cycle and pursue pregnancy.
The Body’s Compensation for a Single Ovary
When one ovary is removed, the remaining one functions more actively to maintain hormonal balance and reproductive function. This compensation allows for regular ovulation, which is the monthly release of a mature egg. The remaining ovary assumes the entire role of egg production, ensuring an egg is available for fertilization each month.
This adjustment is primarily driven by the hormonal feedback loop between the brain and the ovaries. The pituitary gland in the brain releases Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH), which prompt the ovaries to develop follicles and trigger ovulation. After the loss of one ovary, the body adjusts this hormonal signaling to adequately stimulate the single remaining gonad.
Studies show that the concentration of FSH, a marker of ovarian reserve, may be slightly elevated in individuals with one ovary, reflecting the increased effort required by the remaining organ. Despite this shift in hormonal balance, the solitary ovary sustains sufficient estrogen and progesterone production to regulate a predictable menstrual cycle. This compensatory mechanism is robust enough that the age of natural menopause in women with one ovary is similar to those with two, occurring only about one year earlier.
In a typical cycle with two ovaries, the two organs do not strictly alternate in releasing an egg; instead, the dominant follicle is selected from one ovary. With only one ovary, the selection process is localized, and the single organ consistently assumes the responsibility of maturing and releasing the egg. This adaptation means the frequency of ovulation remains unchanged compared to having two ovaries. The remaining ovary demonstrates an increased follicular yield in response to stimulation, confirming its compensatory capacity.
Variables Influencing Conception Success
While the body compensates well, several factors influence the likelihood of conception. The most significant variable is the age of the individual, as ovarian reserve naturally declines over time. Women are born with a fixed number of eggs, and having half the initial number means the pool of available eggs is smaller from the outset.
The underlying reason for the removal of the other ovary plays a role in the health of the remaining one. If the oophorectomy was performed due to conditions like severe endometriosis, the remaining ovary may also be affected, potentially compromising its function. Similarly, if the remaining ovary has pre-existing conditions, such as polycystic ovary syndrome (PCOS), its ability to ovulate regularly may be complicated.
The health and patency of the fallopian tube on the side of the remaining ovary are important for natural conception. For pregnancy to occur, the egg released by the single ovary must be captured by its corresponding fallopian tube, where fertilization usually takes place. If the tube is blocked or damaged, natural conception becomes unlikely, regardless of the ovary’s function.
Overall reproductive health, including the quality of the partner’s sperm, is important for a person with one ovary trying to conceive. For those who require assisted reproductive technology (ART), women with one ovary may have a lower chance of success with in vitro fertilization (IVF) compared to those with two, potentially resulting in a 30% lower live birth rate. This reduced success is attributed to the decreased number of eggs that can be retrieved, even though the quality of the eggs may not be affected.
When to Seek Fertility Assessment and Support
Individuals with a single ovary should consider seeking fertility guidance earlier than the general population. For those under 35, a consultation is recommended after six months of regular, unprotected intercourse without conception. If the individual is 35 or older, seeking an assessment after three months of trying is advised, and immediate consultation is necessary if they are over 40.
Fertility assessments focus on evaluating the function of the remaining ovary and the overall reproductive environment. A blood test to measure Anti-Müllerian Hormone (AMH) levels provides a quantitative estimate of the remaining ovarian reserve. Ultrasound imaging is also used to assess the remaining ovary’s size and Antral Follicle Count, which helps determine the number of resting follicles available for recruitment.
Evaluating the patency of the corresponding fallopian tube is another assessment, often done through procedures like a hysterosalpingogram (HSG). If natural conception is not occurring, medical interventions may involve cycle monitoring and timed intercourse, or the use of ovulation induction medications to encourage the single ovary to release a mature egg.
Should more advanced assistance be needed, assisted reproductive technologies like Intrauterine Insemination (IUI) or In Vitro Fertilization (IVF) remain options. While the number of eggs retrieved during an IVF cycle may be lower than for a person with two ovaries, the protocols can be adjusted to maximize the stimulation of the single ovary. For those who reach the embryo transfer stage, the likelihood of a live birth is comparable to those with two ovaries, suggesting the remaining ovary’s compensatory mechanism is effective.