Table 1: Characteristics of the study population according to breastfeeding initiation in the first and second birth, Nova Scotia, 2007-2013

Factor	Birth 1	Birth 2	Birth 1 breastfeeding initiators (n = 9463)			Birth 1 breastfeeding noninitiators (n = 1997)
Factor	Birth 1	Birth 2	No. breastfed B1	% Did not breastfeed B2	p value	No. did not breastfeed B1	% Breastfed B2	p value
Sociodemographic
Maternal age birth 2, yr, mean ± SD	-		30.3 ± 5.0			26.2 ± 5.1
Smoking	No	No	7075	8.2	< 0.001	940	29	0.01
	No	Yes	246	20.7		86	31.4
	Yes	No	369	13.6		138	28.3
	Yes	Yes	880	24.5		698	22.2
Folic acid	Yes	No	2803	5.6	< 0.001	184	28.3	0.07
	Yes	Yes	1017	8.8		131	26.7
	No	No	994	7.9		161	35.4
	No	Yes	1929	17.8		820	25.2
Maternal obesity	No	No	4333	9.3	< 0.001	840	25.2	0.6
	No	Yes	287	15.7		55	20
	Yes	No	352	11.6		102	29.4
	Yes	Yes	1893	12		455	26.2
High income area	Yes	Yes	4048	7.9	< 0.001	662	27	0.1
	Yes	No	533	13.1		155	34.2
	No	Yes	649	14.3		144	27.1
	No	No	2271	13.6		695	24.7
Rural residence	No	No	3550	8.9	< 0.001	1188	25.6	0.7
	No	Yes	353	12.5		98	28.6
	Yes	No	253	13		75	30.7
	Yes	Yes	2213	13.6		619	27
Married	Yes	Yes	6174	7	< 0.001	588	25.9	0.8
	Yes	No	157	17.8		55	30.9
	No	Yes	1019	14		321	27.7
	No	No	1069	20.4		653	27
Interpregnancy interval	< 18mo		998	17.1	< 0.001	294	24.5	0.4
Interpregnancy interval	≥ 18 mo		8465	9.5	< 0.001	1703	26.7	0.4
Maternal health
Recreational drug use	No	No	9221	10.1	< 0.001	1850	26.1	0.4
	No	Yes	81	17.3		46	37
	Yes	No	123	18.7		83	27.7
	Yes	Yes	38	23.7		18	22.2
Pregestational diabetes	No	No	9390	10.3	0.6	1970	26.3	0.3
	No	Yes	25	12		8	0
	Yes	Yes	40	15.6		13	38.5
Gestational diabetes	No	No	8966	10.1	0.01	1892	26.4	0.6
	No	Yes	248	10.1		56	28.6
	Yes	No	126	17.5		17	11.8
	Yes	Yes	123	16.3		32	28.1
Hyperemesis	No	No	9352	10.2	0.1	1964	26.1	0.09
	No	Yes	62	11.3		18	44.4
	Yes	No	38	18.4		7	57.1
	Yes	Yes	11	27.3		8	25

Labour and delivery factors
Labour S/I	Yes	Yes	7389	9.9	0.03	1144	26.3	0.01
	Yes	No	1479	12		251	23
	No	Yes	188	6.9		15	48.3
	No	No	407	11.8		6	32.2
Cesarean delivery	No	No	6685	9.9	0	1414	25.7	0.06
	No	Yes	464	12.9		111	32.4
	Yes	No	457	4.8		69	37.7
	Yes	Yes	1855	12.2		403	25.1
Ob/Gyn attending	Yes	Yes	4997	11.1	0.01	1069	27.5	0.2
	Yes	No	1144	8		232	27.6
	No	Yes	659	10.9		153	28.1
	No	No	2620	9.4		523	22.9
Postpartum hemorrhage	No	No	8005	10.3	0.6	1711	25.5	0.03
	No	Yes	474	9.1		97	30.9
	Yes	No	837	10.8		170	28.8
	Yes	Yes	147	8.2		19	52.6
Spinal anesthesia	No	No	6533	9.8	0.02	1429	25.7	0.08
	No	Yes	1644	11.6		291	24.4
	Yes	No	567	8.8		84	36.9
	Yes	Yes	719	12.7		193	29.5
Labour and delivery factors (continued)
Epidural anesthesia	No	No	2758	10	0.2	666	27.9	0.06
	No	Yes	532	9.8		117	35
	Yes	No	2919	11.2		597	25.3
	Yes	Yes	3254	9.7		617	24
Intravenous analgesia	No	No	1898	8.9	0.1	448	26.8	0.3
	No	Yes	497	11.7		129	32.6
	Yes	No	1816	10.7		394	26.9
	Yes	Yes	5252	10.5		1026	25.1
Infant factors
Birth sex	-	Male	4921	10.2	0.8	1034	24.6	0.7
Birth sex	-	Female	4542	10.3	0.8	963	24.8	0.7
Birth weight ≥ 2500 g	Yes	Yes	8923	10	< 0.001	1798	25.3	0.01
	Yes	No	163	16.6		63	28.6
	No	Yes	315	14		110	38.2
	No	No	54	18.5		24	41.7
Apgar at 1 min > 6	Yes	Yes	7674	9.9	0.1	1613	24.7	< 0.001
	Yes	No	554	12.1		124	34.7
	No	Yes	1080	11.7		237	31.2
	No	No	155	11.6		23	47.3
Birth year	-	2007-09	3819	9.2	0.01	761	31.7	< 0.001
	-	2010-11	2280	11.6		529	20.4
	-	2012-13	3364	10.6		707	25
NICU admission	-	Yes	192	10.9	0.7	50	44	< 0.001
NICU admission	-	No	9271	10.3	0.7	1947	25.9	< 0.001
Head/neck anomaly	-	No	9440	10.3	0.07	1990	26.3	0.9
Head/neck anomaly	-	Yes	23	21.7	0.07	7	28.6	0.9
Other major anomaly	-	No	9124	10.1	0.03	1900	25.7	0.01
Other major anomaly	-	Yes	339	13.9	0.03	97	38.1	0.01
Gestational age ≥ 37 wk	Yes	Yes	8534	10	0.03	1744	24.6	< 0.001
	Yes	No	329	14.3		79	35.4
	No	Yes	453	12.1		128	37.5
	No	No	108	13		31	51.6
Infant length of stay < 72 h	Yes	Yes	5263	10.4	0.5	1279	22.8	< 0.001
	Yes	No	754	9.7		200	35
	No	Yes	2207	10.7		324	29.3
	No	No	1239	9.3		194	35.6
Hyperbilirubin	No	No	6635	10.6	0	1535	23.8	< 0.001
	No	Yes	804	8.5		156	35.3
	Yes	No	1471	11.5		228	28.1
	Yes	Yes	553	5.8		78	53.8

Note: NICU = neonatal intensive care unit, Ob/Gyn = obstetrician/gynecologist, SD = standard deviation, S/I = spontanous/induced. Columns not adding to total are due to missing values.