The incidence of hypertensive disorders of pregnancy following sperm donation in IVF: an Australian state-wide retrospective cohort study

Study question: Does IVF using donor sperm increase the risk of hypertensive disorders of pregnancy and fetal growth restriction (FGR)?

Summary answer: IVF conceptions arising from sperm donation are not associated with an increased risk of hypertensive disorders of pregnancy or FGR.

What is known already: It has been hypothesized that the absence of prior exposure to factors within the paternal ejaculate increases the risk of preeclampsia and FGR among nulliparous women or women with a new partner-the concept of 'primipaternity'. It remains unclear which element of the ejaculate is responsible: the sperm cell or the constituents of seminal fluid. IVF pregnancies arising from donor sperm where the seminal fluid is absent provide a unique opportunity to test the theory of primipaternity and the relative contribution of the sperm cell. Pregnancies conceived via artificial reproductive technology are at increased risk of preeclampsia and FGR.

Study design, size, duration: Theories about the development of preeclampsia and the relative contribution of spermatic factors were explored by comparing the risk of hypertensive disorders of pregnancy and FGR among IVF pregnancies conceived with autologous gametes (own eggs and partner sperm) and those conceived with donor sperm, donor egg (and partner sperm) and donor embryo. To do this, we performed a retrospective cohort analysis of pregnancy outcomes among singleton pregnancies (n = 15 443) conceived through fertility clinics within Australia between 2009 and 2017.

Participants/materials, setting, methods: All pregnancies resulting in a singleton pregnancy delivering after 20 weeks' gestation were included. The cohort was divided into donor sperm, donor egg and donor embryo (where both gametes came from a donor to create an embryo, or in a surrogate pregnancy) groups. We also compared the data with a control group, defined as IVF-conceived pregnancies from autologous cycles. A multivariable regression model was used to calculate an adjusted odds ratio (aOR).

Main results and the role of chance: The final cohort contained 1435, 578 and 239 pregnancies conceived by donor sperm, donor egg and donor embryo, respectively, and 13 191 controls. There were a very small number of women lost to follow-up (31 women; 0.2% of total cohort). Compared to control pregnancies, there was no increase in the risk of hypertensive disorders among pregnancies conceived via donor sperm (aOR 0.94; 95% CI 0.73-1.21). Subgroup analysis was performed for a cohort where parity was known (n = 4551), and of these, 305 multigravida pregnancies were conceived via donor sperm. Among this cohort, no increased risk of preeclampsia or pregnancy-induced hypertension was found (aOR 1.18; 95% CI: 0.69-2.04) as a result of primipaternity (new sperm donor).A significantly increased risk for hypertensive disorders of pregnancy was associated with the use of donor eggs (but partner sperm; aOR 2.34; 95% CI 1.69-3.21). However, the association was no greater among pregnancies conceived with donor embryos (i.e. donated egg and sperm; aOR 2.0; 95% CI 1.25-3.17) than among the donor oocyte group. The overall incidence of FGR (defined as birthweight <10th centile) was 18%. There were no significant differences observed between donor sperm, or donor embryo pregnancies; however, egg donation was associated with a 1.5-fold increase in FGR.

Limitations, reasons for caution: This study was limited by a lower than expected rate of hypertensive disorders of pregnancy (n = 862, 5.6%), which is contrary to the well-established increased risk among women using IVF. However, this is likely to be evenly distributed across the study groups and, therefore, unlikely to have introduced significant bias.

Wider implications of the findings: These findings suggest that exposure to new sperm may not be implicated in the pathogenesis of preeclampsia. The mechanism of increased risk seen in conceptions arising from egg or embryo donation remains unclear. Further investigation is required to elucidate these mechanisms and, ultimately, improve pregnancy outcomes following IVF.

Study funding/competing interest(s): This study was supported by the Australian Commonwealth Government-Graduate Research Scheme (A.K.). Salary support was provided by the National Health and Medical Research Council of Australia (S.T.), Mercy Foundation (A.L.), and the Department of Obstetrics and Gynaecology at the University of Melbourne (R.H.). There are no competing interests.