Table 1.

Socio-demographic and pre-pregnancy health related predictors of alcohol consumption among pregnancies in Northern Tanzania

	% of pregnancies	Mothers who drank alcohol during the pregnancy
		% drinking alcohol	Univariate analysis		Multivariable model(a)
Variables			RR (95 % CI)	p-value	ARR (95 % CI)	p-value
Total (n = 33006)(b)	100.0	34.1
Mother's age in years (n = 32985)				< 0.001		0.001
17 or younger	2.6	17.4	0.41 (0.35 – 0.48)		0.83 (0.66 – 1.03)
18 – 25	38.9	28.3	0.67 (0.64 – 0.70)		0.93 (0.86 – 1.00)
26 – 35	48.2	37.9	0.89 (0.85 – 0.93)		1.02 (0.97 – 1.08)
36 or older	10.3	42.5	1.00		1.00
Number of previous pregnancies (n = 32029)				< 0.001		< 0.001
0	37.0	26.7	0.65 (0.62 – 0.68)		0.82 (0.77 – 0.87)
1	26.4	36.2	0.88 (0.84 – 0.92)		1.00 (0.95 – 1.05)
2	17.3	41.8	1.02 (0.97 – 1.06)		1.09 (1.04 – 1.15)
3 or more	19.3	41.1	1.00		1.00
Mother's tribe (n = 32961)				< 0.001		< 0.001
Chagga	55.8	45.2	2.07 (1.99 – 2.16)		1.34 (1.27 – 1.41)
Pare	12.6	17.3	0.79 (0.74 – 0.86)		0.92 (0.84 – 1.01)
Maasai	1.0	6.6	0.31 (0.21 – 0.45)		0.88 (0.57 – 1.35)
Other	30.6	21.8	1.00		1.00
Mother's religion (n = 32783)				< 0.001		< 0.001
Catholic	38.6	53.6	3.62 (3.41 – 3.84)		2.91 (2.69 – 3.14)
Protestant	40.0	25.9	1.75 (1.64 – 1.87)		1.59 (1.47 – 1.72)
Muslim	21.4	14.8	1.00		1.00
Mother's Body Mass Index before pregnancy (n = 25417)				< 0.001		< 0.001
< 18.5 Underweight	5.2	23.8	0.58 (0.50 – 0.67)		0.71 (0.62 - 0.82)
18.5 – 24.9 Normal weight	56.8	33.7	0.82 (0.73 – 0.91)		0.86 (0.77 - 0.96)
25.0 – 29.9 Overweight	26.9	41.5	1.01 (0.90 – 1.13)		0.95 (0.85 - 1.06)
30.0 – 34.9 Obese Class 1 (Moderately Obese)	9.3	44.3	1.07 (0.95 – 1.21)		0.97 (0.87 - 1.09)
≥ 35.0 Obese Class 2 (Severely Obese)	1.8	41.3	1.00		1.00
Mother's height (n = 29314)				< 0.001		0.001
< 150 cm	5.5	26.7	0.67 (0.60 – 0.73)		0.81 (0.73 – 0.90)
150 – 159 cm	41.3	33.8	0.84 (0.79 – 0.89)		0.92 (0.86 – 0.97)
160 – 169 cm	45.9	36.8	0.92 (0.87 – 0.97)		0.91 (0.86 – 0.97)
≥170 cm	7.3	40.2	1.00		1.00
Current residence (n = 32913)				< 0.001		0.001
Urban area	52.2	34.4	1.00 (0.97 – 1.04)		1.07 (1.03 – 1.11)
Semiurban area	4.8	28.5	0.83 (0.77 – 0.90)		1.01 (0.92 – 1.11)
Rural area	43.0	34.3	1.00		1.00
HIV status (n = 33006)				< 0.001		< 0.001
Negative	59.4	28.9	0.69 (0.67 – 0.71)		0.91 (0.87 – 0.95)
Positive	3.9	39.3	0.94 (0.87 – 1.00)		1.11 (1.01 – 1.21)
Unknown	36.7	42.0	1.00		1.00
Father's age (n = 32745)				< 0.001		< 0.001
25 or younger	15.1	25.7	0.60 (0.56 – 0.65)		0.82 (0.74 – 0.91)
26 – 35	55.2	33.0	0.77 (0.73 – 0.83)		0.85 (0.79 – 0.92)
36 – 45	25.6	40.5	0.95 (0.89 – 1.02)		0.93 (0.86 – 1.00)
46 or older	4.2	42.6	1.00		1.00
Father's tribe (n = 32835)				< 0.001		< 0.001
Chagga	50.3	45.3	1.85 (1.79 – 1.92)		1.24 (1.19 – 1.30)
Pare	12.5	19.2	0.78 (0.73 – 0.84)		0.94 (0.87 – 1.03)
Maasai	1.4	13.6	0.56 (0.44 – 0.70)		1.00 (0.78 – 1.30)
Other	35.8	24.5	1.00		1.00
Year (n = 33006)				< 0.001		< 0.001
2000	4.8	49.5	2.30 (2.12 – 2.49)		1.88 (1.68 – 2.11)
2001	10.1	44.7	2.08 (1.93 – 2.24)		1.86 (1.68 – 2.07)
2002	9.1	44.9	2.09 (1.94 – 2.25)		1.86 (1.68 – 2.07)
2003	8.1	44.2	2.06 (1.90 – 2.22)		1.72 (1.55 – 1.91)
2004	8.5	39.1	1.82 (1.68 – 1.97)		1.58 (1.42 – 1.76)
2005	8.6	34.9	1.62 (1.49 – 1.76)		1.49 (1.34 – 1.66)
2006	8.9	32.0	1.49 (1.37 – 1.62)		1.46 (1.31 – 1.62)
2007	9.8	28.5	1.33 (1.22 – 1.44)		1.25 (1.12 – 1.40)
2008	10.9	26.2	1.22 (1.12 – 1.33)		1.20 (1.08 – 1.34)
2009	10.8	23.3	1.08 (0.99 – 1.18)		1.02 (0.92 – 1.15)
2010	10.4	21.5	1.00		1.00

^(a)In the multivariable analyses all predictors have been adjusted for mother's age, mother's occupation, mother's tribe, mother's religion, mother's body mass index, mother's height, previous pregnancies, mother's current residence, mother's childhood residence, father's age, father's tribe, year of delivery, drinking water source, boiling of drinking water, mother's age at marriage and mother's HIV-status

^(b) For all the predictors one data entry per pregnancy has been included