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As the average age of first-time US mothers increases, age at first vaginal delivery appears to predict pelvic floor dysfunction and pelvic organ prolapse (POP), a recent review of the limited research on this issue found.

Older primiparous age affects prolapse-related precursor mechanisms including pelvic muscle dysfunction, levator ani muscle (LAM) defects, and genital hiatus enlargement, according to writers of an evidence review in the American Journal of Obstetrics and Gynecology led by Hannah A. Zabriskie, MS, from the Department of Physical Therapy and Athletic Training at the University of Utah, Salt Lake City.

POP can lead to the protrusion of the bladder, uterus, and rectum through the vagina. "Our team's long-term goal is to find methods of prevention for POP, so that women will have options beyond allowing their prolapse to progress to end-stage disease and then pursuing surgical intervention — the current standard of care," Zabriskie told Medscape Medical News. Zabriskie’s group cited a study by Asa Leijonhuvfvud, MD, PhD, and colleagues reporting that women aged 30 years or older at the time of their first vaginal delivery had an increased incidence of POP surgery (13.9%; 95% CI, 12.8%-15.2%) compared with women younger than 30 years at first vaginal delivery (6.4%; 95% CI, 6.0%-6.8%).

Additionally, cesarean delivery had a heightened protective effect in older mothers. Among women aged 30 years or older at first delivery, those with vaginal delivery had an 11-fold increased risk for POP surgery compared with those with cesarean delivery.

The CDC reported 27.5 years as the mean age of US mothers at first birth in 2023, a record high for this country, and according to 2022 US Census Bureau data, the median age of mothers at first birth was 30 years.

Vaginal childbirth at any age is a known risk factor for POP, and 12.5%-20% of women will receive surgical intervention for POP in their lifetimes.

Among other findings in the literature review:

• Anatomic POP remote from first vaginal delivery: In addition to carrying higher odds of symptomatic POP (eg, seeing or feeling a vaginal-area bulge) a study by C. Glazener and colleagues found primiparas aged 30-34 years had 149% greater odds for anatomic problems compared with those aged 24 years or younger; and women aged 35 years or older at first birth had 208% greater odds of anatomic POP vs women aged 24 years or younger.

• POP and genital hiatus enlargement: Heather A. Rosett and colleagues found that genital hiatus enlargement (≥ 4 cm) at 8 weeks postpartum was independently associated with POP 1 year postpartum with a 3.3-fold increase in risk. Women with POP at 1 year postpartum were older.

• LAM defects: Maternal age at first delivery is generally an accepted risk factor for LAM injury. Rohna Kearney and colleagues reported that primiparous women with LAM defect 9-12 months after first vaginal delivery were older than those with intact LAM (32.8 years vs 29.3 years). Not surprisingly, those with a major defect were older than those with a minor defect.

• Age-related tissue impairment: Although Zabriskie’s group found no research specifically addressing primiparous age and tissue defects, studies of cellular and tissue-level changes show that older women with pelvic floor muscle impairment have increased oxidative stress and differential gene expression of extracellular matrix proteins in pelvic floor muscle, the vaginal wall, and the uterosacral ligaments compared with older women without such impairment.

Commenting on the review but not involved in it, Jill M. Rabin, MD, a professor at the Feinstein Institutes for Medical Research, Manhasset, New York, and codirector of the Advanced Clinical Experience in Obstetrics and Gynecology at the Zucker School of Medicine in Hempstead, New York, called it an “amazing, well-written, and well-constructed” analysis. “But it is not new or surprising that the aging process, with and apart from delivery, impacts the structure of muscle and connective tissue and the effectiveness of muscle contraction and support. This review, however, dissects the different elements to explain why we see more prolapse in women who deliver vaginally after 30.”

Rabin noted that although cesarean delivery is protective against POP, it entails risks ranging from infection and hemorrhage to placental implantation in the scar and would only be recommended to prevent POP if a patient had predisposing genetic or clinical features. In her practice, she does not “pathologize prolapse” for patients but she does teach them to maximize their core and pelvic muscle strength before, during, and after recovering from pregnancy and to maintain pelvic floor support between pregnancies. “Core strength can reduce pressure on the pelvic organs,” she said, adding that at the cellular level, it’s also important to support muscle cells with adequate protein intake and good hydration.

Zabriskie and colleagues pointed to the need to identify the cellular, molecular, and transcriptomic differences brought on by age, as well as research to clarify the specific relationship between maternal age at first delivery and the onset and progression of pelvic support impairment. POP risk in younger mothers should also be studied. “Future basic and translational research is essential to identify mechanisms of POP development, thereby enabling both strategies for identifying women at high risk for POP and novel therapeutic strategies that target these mechanisms to aid in pelvic floor tissue recovery postpartum and prevent POP development,” they concluded.

This study received no specific funding. The authors and Rabin had no conflicts of interest to declare.