Table 3.

Differences between sister controls and controls recruited through the general practitioner (GP controls)

	sister controls (n = 313)	GP controls (n = 430)	P value
Age	30 (18–58)	34 (18–54)	<0.001
High education (n/N) (%)	158/308 (51.3)	293/428 (68.5)	<0.001
Is in committed relationship (n/N) (%)	249/311 (80.1)	341/428 (79.7)	NS
Has had intercourse (n/N) (%)	288/312 (92.3)	407/426 (95.5)	NS
Has offspring (n/N) (%)	140/313 (44.7)	201/429 (46.9)	NS
Has previously consulted a gynaecologist for fertility problems (n/N) (%)	29/301 (9.6)	44/411 (10.7)	NS

Data presented as median (range) unless indicated otherwise. NS = not significant.