Are Gestational Carriers at Increased Risk of Pregnancy Complications?

August 25, 2024 Bryan McColgan, MD

Scientific and medical news coverage is hard, but it is even more challenging when covering topics like surrogacy.

A recent news article (1) has tried to sensationalize risks to gestational carriers (GCs) through the title ‘Surrogates more likely to have hypertension and postpartum hemorrhage.’

This news article is referencing an abstract that was published at the 40th annual meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Amsterdam last month (2).

I am thrilled and have been advocating continuously for more GC-specific and assisted reproductive technology (ART)-specific research for queer intended parents. It’s great that this abstract has been published, but I wanted to take this opportunity to give it a bit more medical context, specifically to the limitations in order to de-sensationalize the news article about it.

What Does the Study Show?

Although it would be preferable to have the full article, only the abstract is publicly available, so there are some limitations in how much I can even describe the study design, results, and conclusions.

The study was conducted in Canada using the Ontario Birth Registry from 2012 to 2021. The data included 937,938 pregnancies and deliveries of singletons, with the comparisons being made between the following groups: Unassisted pregnancies (97.7%), IVF pregnancies without a GC (2.2%), and IVF pregnancies with a GC (0.1%).

The primary results were around severe maternal morbidity (SMM) and severe neonatal morbidity (SNM). SMM includes unexpected outcomes of labor and delivery that can result in significant short- or long-term health consequences (3). This broad definition includes less common complications such as a heart attack (or myocardial infarction) and kidney failure and more common pregnancy complications such as eclampsia and hysterectomy (or removal of the uterus) (4). SNM includes any significant complication for the newborn after delivery that requires neonatal intensive care (NICU) and/or results in permanent health complications.

While the study found no differences with respect to SNM and outcomes related to the newborn, the results highlighted differences in the three groups with regard to SMM rates:

2.4% for unassisted pregnancies
4.6% for IVF without a GC
7.1% for IVF with a GC

The study also looked specifically at hypertension (or high blood pressure) in the pregnant women as well as postpartum hemorrhage (or bleeding), which is linked to hypertension. For these results, the rates for each group were:

For unassisted pregnancies: 6.6% for hypertension and 5.7% for postpartum hemorrhage
For IVF without a GC: 11.6% for hypertension and 10.5% for postpartum hemorrhage
For IVF with a GC: 13.9% for hypertension and 13.9% for postpartum hemorrhage.

However, when adjusting these rates, presumable for confounding factors such as the fact that GCs were more likely to have hypertension prior to pregnancy, the adjusted relative risks between groups no longer became significantly different for SMN, but they did remain statistically significant for hypertension during the pregnancy and postpartum hemorrhage.

What Does This Mean?

While I am thrilled that there is GC-specific research, I do not want to draw conclusions that are not thoroughly investigated. I believe that this study has several limitations with regard to its results and conclusions.

The study includes almost a million singleton pregnancies and deliveries, but a very small amount (0.1% or 956) of these are with a GC. This is still a small number, and so there could be more variability and confounding with these GC-pregnancies and deliveries that leads to more extreme outcomes that bias the comparisons.

A major unexplained portion of the study population is that the GCs had higher rates of hypertension prior to the pregnancy. However, the authors do not state what this rate is compared to the other groups, nor do they confirm that if a subgroup analysis was done to remove these pre-pregnancy chronic hypertensive women from the analysis, would the same risk still be present. They do state they adjusted for variables, but as I stated above, with such a small number of GC pregnancies, this adjustment could still result in some bias.

The authors also draw an interesting conclusion that the GCs were more likely to reside in lower income areas. Considering this study is in Canada where gestational surrogacy is altruistic only, it's interesting to me that the authors are trying to bring socioeconomic factors into the picture. These women may be compensated for their lost wages and provided things like maternal clothing to cover costs, but they are not being directed compensated as in the U.S. However, they do mention poorer medical outcomes for lower socioeconomic groups in general, and so it does bring up the question as to where these women delivered. Could they have had more complications because they went to a less affluent or competent hospital? I wrote an article last week comparing maternal mortality rates by country (https://www.babymoonfamily.com/original-articles/maternal-mortality-rates), but there are variations for mortality rates and complications between states and provinces in the U.S. and Canada that should also be accounted for.

One of the most important aspects to this study that I completely agree with is the authors’ claim that eligibility for GCs should be medically consistent.

Interestingly, there are no universal guidelines regarding criteria for choosing a gestational carrier, but the American Society of Reproductive Medicine (ASRM) and the ESHRE state that gestational carriers should not have any chronic medical conditions except adequately treated hypothyroidism (5, 6).

There are no Canadian-specific guidelines, and it appears, based on this study, that they do not adhere to the American or European requirements given that GCs had hypertension. From this perspective, I completely agree with the authors that more regulations and standardization for medical selection of GCs in Canada should be done. This is likely why they found an increase in hypertension during GC pregnancies and postpartum hemorrhage.

However, I strongly caution this study being extrapolated to gestational surrogacy in the U.S. where the standards and selection criteria are more strict. Also, the small sample size of GC pregnancies and other limitations above make these conclusions interesting but not worthy of a sensationalized news article.

It is this focus on the negative and vilification of gestational surrogacy that I am writing to counteract. One of the main goals of BabyMoon Family is to provide objective, actionable, and updated information on all aspects of ART for queer intended parents. This study is an amazing step in the right direction, but the results should be tempered so as to fan the flames of inappropriately negative criticisms of surrogacy around the world.

References: