Conception methods and perinatal outcomes among women with kidney disorders: an Australian population-based cohort...

Do conception methods and related pregnancy outcomes differ between women with and without kidney disease?

In this cohort, 3.3% of births among women with kidney disorders were conceived using ART, 1.9% were conceived following IUI and ovulation induction (OI), and 94.8% were conceived spontaneously; however, women with kidney disorders consistently experienced higher risks of adverse pregnancy outcomes than those without, regardless of conception method.

Kidney disorders can impair fertility and pregnancy outcomes, but population‑level data on the use of medically assisted reproduction (MAR), including ART, IUI, and OI, in this group are limited.

This retrospective cohort study included all live births and stillbirths in New South Wales (NSW) and the Australian Capital Territory (ACT), Australia, between 2009 and 2017.

We used linked state perinatal records to identify births. Kidney disorder diagnoses before delivery were identified using hospital dataset diagnostic coding. Conception mode was classified as (i) spontaneous conception, (ii) IUI/OI, or (iii) ART (including IVF or ICSI or other procedures [e.g. gamete intra-fallopian transfer, surrogacy]) using the Australia and New Zealand Assisted Reproduction Database and the national claims databases for medical services and pharmaceutical dispensing.

During the study period, 911 229 babies were born from 898 084 pregnancies among 606 488 mothers in NSW/ACT. Among these, 10 858 babies (1.2%) were born to 7634 mothers with kidney disorders. Of the babies born to mothers with kidney disorders, 563 babies (5.2%), born to 470 mothers, were MAR-conceived. Women who conceived via MAR were older than those who conceived spontaneously in both groups (kidney disorders: MAR median age 33 (IQR: 30-37) years vs spontaneous median age 29 (24-33), standardized difference (sdiff) = 0.80; non-kidney disorders: MAR median age 34 (31-38) years vs spontaneous median age 31 (27-35), sdiff = 0.71). The most common kidney disorders were renal tubulo-interstitial diseases (MAR: 62.1% vs spontaneous: 72.7%) and urolithiasis (MAR: 36.8% vs spontaneous: 27.2%). The proportion of births conceived using ART was 3.3% among births to women with kidney disorders. The most common MAR treatments were fresh embryo transfers (33.6% kidney disorders vs 37.4% non-kidney disorders), frozen embryo transfers (28.7% vs 29.5%), any OI/IUI (36.0% vs 31.8%), and OI using clomiphene citrate alone (27.0% vs 23.5%). After adjusting for maternal age, parity, Index of Relative Socio-economic Disadvantage, multiple births and pre-existing diabetes, hypertension, and cardiovascular disease, women with kidney disorders had higher odds of caesarean section (MAR: OR 1.49, 95% CI 1.22-1.81; spontaneous: 1.36, 1.29-1.44), preterm birth (MAR: 2.09, 1.62-2.70; spontaneous: 1.76, 1.64-1.89), low birthweight (MAR: 1.69, 1.27-2.27; spontaneous 1.54, 1.41-1.67), and low Apgar scores (MAR 1.37, 1.06-1.79; spontaneous 1.17, 1.09-1.26) than women without kidney disorders, regardless of conception method.

As our study included only women who achieved a birth, it did not include those who underwent MAR but did not conceive or those who experienced miscarriage; therefore, MAR success rates could not be assessed. The association between kidney disorders and adverse pregnancy outcomes should not be interpreted as causal.

Although most births among women with kidney disorders were spontaneously conceived, MAR was utilized by a substantial proportion of women with and without kidney disorders, particularly among older women. Women with kidney disorders experienced higher risks of adverse pregnancy outcomes regardless of conception method, emphasizing the importance of early identification and specialized multidisciplinary care throughout the reproductive journey.

This study is funded by the Australian National Health and Medical Research Council (APP1127437).

The National Perinatal Epidemiology and Statistics Unit (NPESU) at University of New South Wales (UNSW) received funding from the Fertility Society of Australia and New Zealand (FSANZ) to prepare annual and benchmarking reports using data from the Australian and New Zealand Assisted Reproductive Technology Database (ANZARD). G.M.C is the Director of the NPESU and an employee of UNSW. W.L. is a deputy editor for Human Reproduction. The remaining authors have no relevant disclosures for this study.

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