Exploring the impact of maternal asthma on placental hormones and placental weight

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Placental hormones and placental weight can both have a significant impact on pregnancy outcomes, yet the relationship between them has not been well-defined, especially in the context of maternal asthma. A team of investigators with the University of North Dakota School of Medicine & Health Sciences presented poster findings at the American College of Obstetricians and Gynecologists 2024 Annual Clinical & Scientific Meeting (ACOG 2024) in San Francisco, California, from May 17-19, 2024, that focused on defining the connection between placental hormones, weight, and asthma.¹

Using prospective observational cohort data from the B-WELL-Mom study, investigators sought to uncover whether asthma modifies the association between placental hormones and placental weight. Data on placental weight were obtained from placental pathology reports, while participants underwent blood draws at ~30 weeks of gestation (range, 26–36 weeks) to determine pregnancy hormone levels from serum. In particular, investigators were interested in those hormones that regulate and influence placental function, including prolactin (in nanograms per milliliter [ng/mL]), lactogen (in ng/mL), placenta growth hormone (PGH) (in picograms per milliliter [pg/mL]), IGF-1 (in pg/mL), and IGF-2 (in ng/mL).

After pooling data for 174 women (134 with asthma, 40 without), investigators relied on linear regression models to chart the associations between placental hormones and weight, broken out by demographic and pregnancy characteristics. Those models were then stratified by asthma status.

Study participants had an average age of 31 years, were racially diverse (40% White, 40% Black, 15% Hispanic, 5% mixed race), and had a higher income (47%; >$140,000). The mean placental weight among all participants was 465.56 g. The placental weight did differ based on maternal asthma status. Individuals with asthma had a higher placental weight compared with individuals without asthma (473.43 g compared with 439.20 g; P< .05).

When examining pregnancy hormone levels overall via regression analysis, investigators identified a strong association between high PGH and increased placental weight (68.32 g; 95% CI, 24.23, 112.40). In women without asthma, that link between increased PGH and placental weight was stronger (127.47 g; 95% CI, 19.22, 235.72) compared with women with asthma (66.18 g; 95% CI, 16.33, 116.03; P-interaction= .12).

Investigators concluded that asthma status does, in fact, impact the association between PGH and placental weight, specifically that the relationship between the 2 is stronger in pregnant individuals without asthma. The findings underscore the complexities of managing pregnant patients with comorbidities and emphasize the need for additional research on the interplay between asthma and placental function.

References

Hanson C, Saizy S, O’Hare D, Schlichting R, Subramaniam A, Williams A. Does maternal asthma modify the association between placental hormones and placental weight? Poster presented at: The American College of Obstetricians and Gynecologists 2024 Annual Clinical & Scientific Meeting. San Francisco, CA. May 17-19, 2024.