Boy in the womb: higher risk of preeclampsia? Large study finds link to severe course

Preeclampsia is one of the most dangerous complications of pregnancy: it raises blood pressure, damages organs, and continues to cause thousands of maternal deaths each year. A new paper in Scientific Reports adds an unexpected twist to the risk profile: Women who gave birth to a boy were more likely to develop severe preeclampsia than those who gave birth to a girl, even after accounting for other factors. It’s not a “cause” but an associated marker, but it could help with early risk stratification.

The study was conducted in Eastern Sudan (Gedarif Maternity Hospital) in 2021-2023. Case-control design: 300 women with severe preeclampsia and 600 healthy pregnancies as controls; data were collected by interviews, analyzed by multivariable logistic regression according to STROBE standards. Result: among cases of severe preeclampsia, the proportion of male newborns was higher (69.7% versus 54.5%), and the adjusted odds ratio was AOR 1.65 (95% CI 1.14-2.39).

• Who falls into the higher risk group (according to the authors’ model):
  • Male gender of the newborn → AOR 1.65.
  • First pregnancy (primiparity) → AOR 2.43.
  • Higher maternal BMI (per unit) → AOR 1.12.
  • Low education and housewife status are also associated with risk (the model yields very high AORs, which may reflect the social boundaries of the sample and the coding of variables).

Background of the study

Preeclampsia remains one of the leading causes of maternal and perinatal mortality worldwide: according to WHO estimates, it affects about 2-8% of pregnancies and is associated with tens of thousands of maternal deaths and hundreds of thousands of fetal/newborn losses each year. The burden is particularly high in resource-poor settings where access to early diagnosis and timely treatment is limited. In this context, finding simple markers for risk stratification is the number one challenge for obstetric services.

One potential marker that regularly surfaces in the literature is fetal sex. Several meta-analyses and cohort studies have shown that male pregnancy may be associated with higher rates of preeclampsia or its severe forms in certain populations, although the data are heterogeneous and depend on racial-ethnic composition and other maternal factors. This supports the idea that fetoplacental characteristics (immune settings, hormonal production, placentation patterns) contribute to the clinical course of the disease.

The new Sudanese paper in Scientific Reports fits into this context: the authors use a case-control design in a real-world clinical setting where the incidence of severe preeclampsia is high, and assess the contribution of the neonate’s sex against the background of already known risk factors (primiparity, increased BMI, etc.). This approach allows not only to test the reproducibility of the association in a different demographic, but also to understand whether information about the fetus’s sex adds prognostic value to conventional clinical predictors in resource-limited settings.

It is important to emphasize that no observational study proves causality: the “male fetus - higher risk” association may reflect more complex mechanisms of interaction between the mother and placenta, as well as social and behavioral characteristics of the population. However, if the association is stable, it can be used as part of a multifactorial model of early monitoring - together with control of body weight, blood pressure and obstetric history - to timely strengthen surveillance and prevention of complications.

What is "severe" preeclampsia in this paper?

The authors considered a case to be “severe” if, in addition to hypertension, at least one of the following signs appeared: severe headache, visual/neurological impairment, severe liver/kidney dysfunction, pressure ≥160/110 mm Hg, thrombocytopenia <100×10⁹/l. That is, we are talking about clinically serious conditions that require active management.

• What the design looked like (briefly):
  • Place and time: Gedarif, East Sudan; May 2021 - August 2023.
  • Groups: 300 cases vs 600 controls, single pregnancies ≥20 weeks.
  • Instruments: standardized questionnaires, medical records; regression adjusted for obstetric and socio-demographic factors.

What this might mean in practice

The association "boy - higher risk of severe preeclampsia" is consistent with the idea that fetal and placental factors influence the course of pregnancy (immune interactions, placental hormones, etc.). This does not mean that "boys cause preeclampsia", but it does suggest that if other risk factors are present (high BMI, first pregnancy), fetal sex may be considered when planning monitoring.

• What clinicians can do now (without changing the guides):
  • In case of a combination of primiparity + high BMI + male sex of the fetus, consider more frequent visits/home BP monitoring.
  • Strengthen educational activities for vulnerable groups (low level of education/resources), as social factors also “pull” the risk upward.
  • Remind patients of the “red flags” of severe preeclampsia (headache, “floaters,” pain under the right costal margin) and thresholds for immediate medical attention.

Why exactly could it turn out this way?

There is evidence that pregnancy with a boy is often accompanied by a greater placental load and a different immune system in the mother; in some populations, boys have a higher risk of adverse perinatal outcomes. Sudan is a country with a high proportion of preeclampsia and social contrasts, so biological and social factors could have worked “in one direction”. The authors, by the way, find references to similar observations in certain groups (for example, in black American women), but admit that the picture is not universal and differs between racial-ethnic and national samples.

• Strengths of the work:
  • Large sample size for a single-center study (n=900) and “rigorous” definition of severe cases.
  • Transparent statistics and STROBE compliance.
• Weaknesses and caution in interpretation:
  • Observational design - speaks of connection, not causation.
  • One institution and region → question of generalizability to other countries/health systems.
  • Very large AORs for social variables indicate possible residual confounding and coding peculiarities.

Summary

In the Sudanese case-control study, being pregnant with a boy was associated with increased odds of severe preeclampsia (AOR 1.65) – along with familiar factors such as first pregnancy and high BMI. This is another piece of the puzzle that shows that fetal characteristics influence maternal risk. The next step is multicentre studies in different populations and the integration of fetal sex into personalised risk models.

Source: Adam GK et al. Male newborn as a determinant of severe preeclampsia: a case-control study. Scientific Reports 15:30054 (published 17 August 2025). https://doi.org/10.1038/s41598-025-16346-1