Table 3.

Effect modification by prepregnancy obesity and maternal history of CVD on the association between history of GDM and subsequent CVD in Danish women

Effect modifier	Exposure	No. of CVD cases	Rate per 1,000 person-years	HR (95% CI) model 1	HR (95% CI) model 2
Prepregnancy obesity*	No history of GDM and no prepregnancy obesity	179,385	10.78	1.0 (Reference)	1.0 (Reference)
	History of GDM only	2,651	16.85	1.69 (1.63–1.76)	1.43 (1.38–1.49)
	Prepregnancy obesity only	3,420	13.17	1.81 (1.75–1.87)	1.49 (1.44–1.54)
	History of GDM and prepregnancy obesity	364	16.76	2.29 (2.07–2.54)	1.76 (1.59–1.95)
	Multiplicative interaction (GDM × obesity)			0.75 (0.67–0.84)	0.82 (0.74–0.93)
	P for multiplicative interaction			<0.001	0.001
	RERI			−0.21 (−0.46 to 0.04)	−0.16 (−0.36 to 0.03)
	P for additive interaction			0.099	0.104
Maternal history of CVD†	No history of GDM and no maternal CVD	53,741	9.25	1.0 (Reference)	1.0 (Reference)
	History of GDM only	864	13.46	1.59 (1.49–1.70)	1.31 (1.23–1.40)
	Maternal CVD history only	98,837	11.67	1.17 (1.16–1.18)	1.22 (1.21–1.23)
	History of GDM and maternal CVD	1,572	18.77	2.04 (1.94–2.14)	1.75 (1.66–1.84)
	Multiplicative interaction (GDM × CVD)			1.10 (1.01–1.19)	1.09 (1.00–1.19)
	P for multiplicative interaction			0.032	0.042
	RERI			0.28 (0.13–0.43)	0.21 (0.09–0.34)
	P for additive interaction			<0.001	0.001

Model 1: Follow-up time as time scale.

^*Model 2: Follow-up time as time scale, controlled for time period of first delivery, parity, age at first delivery, education, smoking during pregnancy, cohabitation, residence, country of origin, maternal CVD history, and paternal CVD history.

^†Model 2: Follow-up time as time scale, controlled for time period of first delivery, parity, age at first delivery, education, smoking during pregnancy, cohabitation, residence, prepregnancy obesity, country of origin, and paternal CVD history.