Table 1.

Population characteristics

	No fibroids group 1 (reference group)	Fibroids before pregnancy no operation group 2	Fibroids after pregnancy group 3	Fibroid operation before pregnancy group 4
Population, N	91 292	124	963	317
Age, years Mean (SD)	30 (4.29)	34 (4.15)	32 (3.96)	34 (4.16)
BMI, kg/m2 median (range)	23 (10–64)	23 (16–40)	23 (16–49)	22 (18–35)
Parity median (range)	1 (0–14)	1 (0–3)	1 (0–5)	0 (0–3)
Smoking, %	16.43	11.82	16.04	13.15
Fertility treatment, %	6.32	18.48	9.76	39.39
Multiple pregnancy, %	2.14	4.03	3.95	7.89