Gastrointestinal polyposis syndromes represent a group of genetic disorders characterized by numerous adenomas in the colon and small intestine. In familial adenomatous polyposis (FAP), the most frequent syndrome, patients have an almost 100% lifetime risk of colorectal cancer. Prophylactic proctocolectomy is typically performed during the phase of relationship formation and family planning. This study examined whether polyposis syndromes and proctocolectomy affect relationship status, family formation, fertility, and reproductive outcomes compared with the general population.

Patients from a tertiary polyposis outpatient clinic (FAPHD cohort) completed an anonymous standardized questionnaire assessing relationship status, number of children, fertility treatment, miscarriages, and colectomy status. Data were compared with the „Family Research and Demographic Analysis“ (FReDA) cohort, a nationwide dataset of German adults, with focus on marital and partnership situations during the family formation phase. Student’s t-test and Pearson’s chi-square-test with Yates’ continuity correction were used to assess group differences. Negative binomial regression was applied to evaluate age-adjusted differences in fertility, and results were verified by age-grouped analysis.

155 FAPHD patients (87 women, median age 50 years, range 18–85) and 21,265 FReDA participants (11,939 women, median age 37 years, range 18–55) provided complete data. Relationship status did not differ significantly between cohorts (79.4% FAPHD vs. 76.6% FReDA; p=0.48).

Among women, 58.6% in FAPHD had children compared with 51.8% in FReDA (p=0.24). Crude fertility rates were similar (1.06 vs. 0.96 children per person in FAPHD and FReDA, respectively; p=0.24). However, subgroup analysis of 53 female FAPHD patients aged 18-55 showed a decreased fertility rate (0.66; p=0.01). Age-adjusted analyses confirmed a lower annual fertility increase in FAPHD (3.47% vs. 7.1%; p=0.001), resulting in a lower predicted fertility rate above age 27.7. Age-grouped analyses showed significantly lower estimated fertility rates in FAPHD women aged 40-45, 45-50, and 50-55 years (-0.64, -1.08, and -0.96; all p<0.03).

In the FAPHD cohort, 124 of 155 patients had undergone proctocolectomy. Post-proctocolectomy patients were more likely to be in a relationship (83.1%; p=0.042), while parenthood rates did not differ. Use of fertility treatment did not differ significantly among women (18.4% FAPHD vs. 14.5% FReDA; p=0.38). Lifetime miscarriage was reported by 21.8% of FAPHD women vs. 4.7% in FReDA. However, the FReDA questionnaire captured only miscarriages occurring within the 14-year survey period. 

Polyposis syndromes and proctocolectomy do not appear to impede relationship status. In patients with polyposis, those who had undergone proctocolectomy were even more frequently in a relationship, likely because surgery is usually performed at younger ages, when long-term relationships typically form. However, age-specific analyses revealed a reduced fertility increase in FAPHD, especially beyond 40 years. Despite this, the use of fertility treatment was comparable to that in the general population.