. 2019 Jul 9;9(7):e026220. doi: 10.1136/bmjopen-2018-026220

Table 3.

Associations between the risk of new large-for-gestational age (LGA) birth in the second pregnancy following a non-LGA birth in the first pregnancy and change in maternal body mass index (BMI) between pregnancies measured at the first antenatal visit of each pregnancy stratified by BMI category in the first pregnancy

Maternal BMI change (categorised)		Full sample			Underweight at first pregnancy			Normal weight at first pregnancy			Overweight at first pregnancy			Obese at first pregnancy
Maternal BMI change (categorised)		Total n, No of cases	Relative risk, (RR)^*	95% CI	Total n, No of cases	RR^*	95% CI	Total n, No of cases	RR^*	95% CI	Total n, No of cases	RR^*	95% CI	Total n, No of cases	RR^*	95% CI
Total unadjusted n, No of cases		14 788, 1573			606, 24			8888, 812			3458, 454			1836, 283
Lost ≤ −1 kg/m² from previous pregnancy	Unadjusted	2351, 232	1.05	0.91 to 1.22		–	–	1163, 85	0.88	0.68 to 1.14	690, 79	0.95	0.73 to 1.24	477, 68	0.90	0.67 to 1.23
Lost ≤ −1 kg/m² from previous pregnancy	Adjusted^†	2258, 222	0.94	0.80 to 1.10	–	–	–	1108, 81	0.87	0.68 to 1.12	663, 76	0.96	0.72 to 1.29	466, 65	0.95	0.67 to 1.34
Weight stable (> –1 to <1 kg/m²)	Unadjusted	5411, 508	Ref		244, 7	Ref		3680, 305	Ref		1024, 123	Ref		463, 73	Ref
Weight stable (> –1 to <1 kg/m²)	Adjusted^†	5191, 489	Ref		234, 7	Ref		3519, 292	Ref		985, 118	Ref		453, 72	Ref
Gained 1–3 kg/m² from previous pregnancy	Unadjusted	4122, 450	1.16	1.03 to 1.31	230, 8	1.21	0.45 to 3.29	2606, 259	1.20	1.02 to 1.40	888, 127	1.19	0.94 to 1.50	398, 56	0.89	0.65 to 1.23
Gained 1–3 kg/m² from previous pregnancy	Adjusted^†	3944, 427	1.13	0.99 to 1.28	222, 7	1.04	0.36 to 3.04	2497, 251	1.26	1.06 to 1.50	839, 115	1.16	0.89 to 1.50	386, 54	0.86	0.61 to 1.22
Gained ≥3 kg/m² from previous pregnancy	Unadjusted	2904, 383	1.40	1.24 to 1.59	111, 9	2.83	1.08 to 7.40	1439, 163	1.37	1.14 to 1.64	856, 125	1.22	0.96 to 1.53	498, 86	1.10	0.82 to 1.46
Gained ≥3 kg/m² from previous pregnancy	Adjusted^†	2822, 364	1.34	1.17 to 1.54	104, 6	2.08	0.67 to 6.51	1389, 151	1.34	1.09 to 1.65	839, 123	1.35	1.05 to 1.75	490, 84	1.21	0.89 to 1.65

*Generalised linear model with log link and robust variance estimator used to derive RR.

†Adjusted for maternal age, ethnicity, highest educational qualification, whether undergone infertility treatment, smoking status, employment status, baseline BMI, gestational diabetes in current pregnancy and interpregnancy interval.

Bold fonts indicate statistical significance at 0.05 level.