HELSINKI, FINLAND (FRONTLINE MEDICAL NEWS) – The overall birth rate within 5 years of initiating fertility treatment with homologous gametes was 71% among nearly 20,000 women in a Danish assisted reproductive technology registry.

Conception occurred after treatment in 57% of the women, and conception was spontaneous in 14%, Sara Malchau, MD, reported at the annual meeting of the European Society of Human Reproduction and Embryology.

The findings allow physicians to give couples a comprehensible, age-stratified, long-term prognosis at the start of treatment, said Dr. Malchau of Copenhagen University Hospital, Hvidovre, Denmark.

To assess long-term outcomes, Dr. Malchau and her colleagues identified all women in the mandatory Danish ART Registry who initiated fertility treatments with homologous gametes in pubic and private clinics in Denmark between 1997 and 2010. The 19,884 subjects’ treatment cycles were cross-linked with the country’s Medical Birth Registry to identify live births after treatment and spontaneous conception. Follow-up was available for up to 2 years for all of the women, up to 3 years for 14,445 women, and up to 5 years for 5,165 women.

The total live birth rates at 2, 3, and 5 years after the first treatment using ART or intrauterine insemination (IUI) were 57%, 65% and 71%, respectively. Dr. Malchau reported.

In women who had ART as the first treatment, the corresponding ART-conception live birth rates were 46.1%, 51.1%, and 52.9%, and the birth rates with spontaneous conception and IUI after 5 years were 11.2% and 0.6%, respectively.

In those with IUI first, 34.2% delivered after IUI conceptions within 2 years, with no significant increase in birth rates after 3 and 5 years. Shifting to ART in these women resulted in birth rates for ART conceptions of 15.1%, 21.1%, and 23.7% after 2, 3, and 5 years, respectively. After 5 years, the birth rate from spontaneous conception in all women starting treatment with IUI was 16.6%, she noted.

Stratification by age showed that the birth rates at 5 years were 80% for women under age 35 years, 60.5% for those aged 35-40 years, and 26.2% for those aged 40 and older.

While the national ART registry in Denmark is compulsory, underreporting can occur. However, it is cycle based, and since most women have repeated treatments, is it unlikely that the number of women with no birth was underestimated in this study, Dr. Malchau noted.

The findings – which reflect the Danish treatment strategy of three to six cycles of IUI followed by ART, explaining why birth rates after IUI did not increase after 2 years – help answer important patient questions, she said.

“Infertility patients have two key questions: What are our chances of having a baby and when will it happen?” said Dr. Malchau. “Overall chances of a live birth are good, but successful treatment takes time. Couples will often need several treatment cycles. And even though the greatest chance of conception is following treatment, there is still a reasonable chance of spontaneous conception.”

Spontaneous conception is most common in women under age 35 starting IUI (IVF statistics: 18% vs. 8% in those over 35 starting IVF treatment).

The findings are “robust and realistic,” and since those undergoing treatment have no idea how many treatment cycles they will need or have, a “prognosis based on fixed points in time better reflects their prospect of conception and delivery than birth rates after different numbers of attempts,” Dr. Malchau said.

Copenhagen University Hospital Hvidovre and Ferring Pharmaceuticals funded the study.