Getting Pregnant With One Ovary: Why the Cause Matters

Usually, yes. One ovary ovulates, makes the same hormones and responds to fertility drugs, and the remaining ovary measurably recruits more follicles than it would have done with a partner. What the count does not tell you is the prognosis. Why the ovary is gone, and how old you were when it went, matter more than the fact that there is one.

The largest study of the question followed every Swedish woman born between 1955 and 1966 to the end of reproductive age. Among 10,469 who had one ovary removed for a benign reason, 25.5% gave birth afterwards, against 28.7% of 101,753 women of the same age with both ovaries. In the group who had not yet had a child at the time of surgery, the gap was much larger: roughly four in ten went on to give birth, against roughly two in three of the comparison group.

That is an association, not a cause, and the authors say so plainly. They could not tell who was trying to conceive, and they could not see what was wrong with the ovaries that were taken out — which is precisely the thing most likely to explain the gap.

An ovary can be absent for reasons that say nothing about the other one, and for reasons that say a great deal. Sorting out which applies is the single most useful thing a first consultation does.

• Removed for a benign cyst, a dermoid, or after torsion. The remaining ovary is usually normal. In a systematic review of 113 surgically confirmed cases of ovarian absence, torsion or a vascular event was the suspected cause in about half, and the authors conclude that fertility is likely minimally or not affected where absence is one-sided.
• Absent from birth. The same review found that imaging had missed the abnormality in more than a quarter of cases that had pre-operative scans, that about one in six had a uterine anomaly and about one in five a kidney anomaly, and that renal anomalies clustered with uterine ones. So a congenitally absent ovary is a reason to look at the uterus and kidneys, not a reason to expect low fertility.
• Removed as part of endometriosis surgery. Here the disease, not the missing ovary, drives the outlook. A meta-analysis of 12 prospective studies in 783 women found AMH fell by about two-fifths from baseline after one-sided endometrioma removal and by more than half after both-sided removal, and that the drop persisted. Pre-operative AMH was no different between the two groups, which argues the surgery does the damage rather than the cyst.
• Removed for cancer or suspected cancer. This page does not cover it. The Swedish register study deliberately excluded malignant indications, so its numbers do not transfer.

There is an Indian layer to this. A systematic review of 89 hysterectomy audits published between 2010 and 2024 found that about a quarter of hysterectomies in India were done in women under 40, that abnormal uterine bleeding and fibroids were the leading indications, and that oophorectomy was frequently performed without any documented ovarian pathology. If you were not told why an ovary was taken, ask for the operation notes and the histopathology report. They change what the number above means for you.

Fewer than two ovaries would have given, but more than half as many. A historical cohort compared 51 women who had one ovary with 102 women who had both, matched two to one. Baseline FSH, oestradiol and antral follicle counts were no different between the groups. The two-ovary group produced more follicles and more eggs in total, as you would expect. But when the single ovary was compared with only the matching ovary of the controls, the single ovary had a higher antral follicle count and produced more follicles and more eggs — and it was more likely than the control ovary to beat the median. Live birth rates in the two groups were similar.

That is what compensation looks like when it is measured rather than asserted: partial, real, and not enough to make one ovary equal two on yield. It is also a cohort of 51 women at one academic clinic, which is a reason to treat it as encouraging rather than settled. Your AMH and antral follicle count on the remaining ovary tell you far more about the likely yield than the ovary count does.

Somewhat, and that matters because it shortens the window rather than the monthly chance. In a Norwegian population study of 23,580 women, those who had had one ovary removed reached menopause at a mean of 49.6 years against 50.7 years in the rest — about a year earlier, an effect the authors compare in size to smoking and describe as weaker than the loss of half the follicle pool would predict. They read that as evidence of compensation in the remaining ovary.

A later Canadian cohort of 23,630 women, 548 of whom had had one ovary removed, found a stronger signal in the women operated on young: the adjusted hazard of earlier menopause roughly doubled when surgery happened between about 20 and 40, and the adjusted odds of premature ovarian insufficiency were 3.75 times higher than in the rest of that cohort (95% CI 1.72-8.16). Both studies relied on self-reported surgery or survey data. Taken together they support bringing plans forward rather than assuming nothing has changed.

This is the part most pages leave out, and on this topic it is the part that stops you being sold something.

• That the missing ovary itself causes the lower childbirth rate. The Swedish study is observational. It could not adjust for the disease that led to surgery, could not see the removed ovaries' pathology, had no lifestyle data for most participants, and could not tell who wanted a pregnancy. Its authors state that causality cannot be inferred.
• That ovaries alternate month by month. Nothing in the retrieved evidence supports the common claim that each ovary takes a strict monthly turn, or that the remaining one "takes over" every month. The measured finding is follicular recruitment, not a rota.
• That there is a monthly conception rate for one ovary. No figure for natural fecundability or time to pregnancy with one ovary versus two appeared in any source retrieved for this page. If a clinic quotes you one, ask which study it comes from.
• That diet, supplements or stress reduction change the outcome here. None of the sources on this page tested them in women with one ovary. General preconception advice still applies; it is not a treatment for having one ovary.
• That one ovary is a reason for IVF. It is not, on its own. Sometimes the answer is testing, timing, or a simpler treatment than IVF. The reason to escalate is a blocked tube, a sperm problem, age, or time spent trying — not the ovary count.

Worth writing down before you go. Losing an ovary is often remembered as a single sentence from a surgeon years earlier, and the detail is what a fertility assessment needs.

1. The operation note and the histopathology report for the ovary that was removed, and your age at the time. Benign cyst, torsion and endometriosis lead to different expectations.
2. AMH and an antral follicle count on the remaining ovary, plus a scan that reports whether that ovary looks normal and whether the uterus does.
3. Whether the tube on the remaining side is open. If one ovary and the opposite tube were removed, tubal patency becomes the question that actually decides the route.
4. If the ovary went during endometriosis surgery: whether there is residual disease, and whether any further surgery is being proposed. The AMH figures above are an argument for caution about repeat cystectomy.
5. Whether anything argues for moving faster given the menopause-timing data, rather than waiting a standard twelve months.

One thing worth saying out loud: being told at 25 that an ovary has gone, and then reading a register study with a 25-point gap in it, is frightening in a way a percentage does not convey. The gap is largest in women operated on late and in women who had not yet had a child, and it is not adjusted for the disease that caused the surgery. It is a reason to be assessed sooner. It is not a verdict.