Natural Conception in Turner Syndrome
Women with Turner syndrome (45,X) have an extremely low chance of natural conception, with only approximately 1-2% ever achieving spontaneous pregnancy, and the vast majority will require oocyte donation for motherhood. 1, 2
Baseline Ovarian Function in Turner Syndrome
Turner syndrome is fundamentally characterized by accelerated oocyte loss and ovarian dysgenesis. While normal numbers of oocytes develop during fetal life, they begin disappearing due to abnormal meiotic division from the lack of a pairing X-chromosome. 2
However, natural conception remains possible in a small subset:
- 40-50% of girls with Turner syndrome demonstrate some pubertal development 2
- Approximately 10% may undergo menarche spontaneously 2
- Ovarian follicles can be found in about 40% of teenagers with Turner syndrome 2
- Spontaneous pregnancies occur in 2-10% of women with Turner syndrome, which is higher than previously estimated 2
The literature documents only two women with Turner syndrome who achieved spontaneous pregnancy after developing amenorrhea and elevated gonadotropins with streak ovaries—an extraordinarily rare occurrence. 1
Prognostic Factors for Retained Ovarian Function
Positive indicators for the presence of functional oocytes include: 2
- Mosaic karyotype or structural chromosomal abnormalities (rather than pure 45,X)
- Detectable serum antimüllerian hormone (AMH)
- Normal or near-normal follicle-stimulating hormone (FSH) levels
- Spontaneous onset of pubertal development
Women with these favorable features have the highest likelihood of natural conception, though it remains uncommon.
Critical Distinction from Other Forms of POI
It is essential to counsel women with Turner syndrome differently than women with 46,XX premature ovarian insufficiency. 1 While the term "primary ovarian insufficiency" accurately describes 46,XX patients who often retain some follicular reserve and have 5-10% spontaneous pregnancy rates, amenorrheic women with Turner syndrome truly have ovarian failure. 1 Giving them the same hope for spontaneous pregnancy as women with 46,XX POI would be misleading and unfair. 1
Fertility Preservation Considerations
For the minority of Turner syndrome patients with mosaic karyotypes and retained ovarian function: 3
- Fertility preservation may only be feasible for young patients with mosaic Turner syndrome who still have detectable ovarian reserve 3
- By the time most patients reach puberty, their primordial follicle reserve is already depleted, making fertility preservation impossible 3
- FSH-stimulated oocyte retrieval and cryopreservation should be performed before predicted premature ovarian failure in those rare candidates 2
Established Fertility Options
For the vast majority of women with Turner syndrome seeking motherhood: 3
- Oocyte donation is the established and mainstream option 3
- No interventions have been reliably shown to increase ovarian activity and natural conception rates 3
- Adoption remains an alternative 4
Critical Safety Considerations
Any pregnancy in Turner syndrome—whether spontaneous or through assisted reproduction—carries extreme maternal risk: 1, 5
- Maternal mortality from aortic dissection is estimated at 2% during pregnancy 5
- This represents an approximately 100-fold increase in maternal mortality compared to the general population 1
- All women with Turner syndrome are at risk of aortic rupture during pregnancy, regardless of prior spontaneous menses, age >30 years, or absence of known cardiovascular abnormalities 1
- Aortic dissection can occur at smaller aortic diameters than in other populations 1
Mandatory preconception evaluation includes: 3, 6
- Assessment by a cardiologist with specialist interest in adult congenital heart disease 3
- Cardiac MRI to evaluate for bicuspid aortic valve, coarctation, and aortic dimensions 6
- Blood pressure, renal function, and thyroid function assessment 3
- Comprehensive counseling about the 2% maternal mortality risk 5