Are the timings and risk factors changing? Survival analysis of timing of first antenatal care visit among pregnant women in Nigeria (2003–2013)

Figures & data

Table 1 Distribution of the pregnant women studied, by characteristics and the DHS year

Characteristics	Total =45,690		2003	2008	2013
	n	%	4,167	19,340	22,183
Age, years
15–19	3,777	8.3	9.7	8.3	7.8
20–24	9,018	19.7	20.7	19.7	19.6
25–34	20,667	45.2	44.9	45.3	45.3
35–49	12,229	26.8	24.7	26.7	27.3
Mother education
No education	21,502	47.1	48.5	47.6	45.7
Primary	9,857	21.6	23.4	22.3	19.9
Secondary	11,577	25.3	23.8	24.2	27.7
Higher	2,755	6.0	4.4	5.8	6.8
Marital status
Never	1,582	3.5	3.9	3.4	3.4
Married/LWSP	42,666	93.4	92.1	93.6	93.4
Formerly married	1,441	3.2	4.1	3.0	3.1
Religion
Islam	23,798	52.1	15.2	54.2	57.9
Xtian	18,679	40.9	24.5	43.4	40.7
Others	3,213	7.0	60.4	2.5	1.4
Tribe
Hausa/Fulani	16,772	36.7	30.0	36.0	39.7
Yoruba	5,391	11.8	11.3	12.0	11.6
Igbo	4,714	10.3	12.0	10.3	9.9
Others	18,813	41.2	46.7	41.7	38.9
Involved in her income spending
Yes	22,093	86.9	90.6	84.3	89.9
No	3,332	13.1	9.5	15.7	10.1
Involved in her health care decision
Yes	16,248	37.9	23.6	40.7	36.8
No	26,679	62.2	76.4	59.3	63.2
Residence
Urban	13,679	29.9	35.4	27.1	33.6
Rural	32,011	70.1	64.6	73.0	66.4
Zone
North Central	7,700	16.9	16.5	18.1	14.8
North East	9,685	21.2	22.4	21.8	19.8
North West	13,073	28.6	30.0	26.5	32.0
South East	3,774	8.3	8.1	8.4	8.1
South South	5,661	12.4	11.1	12.5	12.6
South West	5,797	12.7	11.9	12.8	12.7
Distance to health facility is a problem
ig problem	16,476	36.2	25.6	40.1	32.2
No problem	29,035	63.8	74.4	60.0	67.8
Working
Yes	31,180	68.5	65.0	68.0	70.5
No	14,311	31.5	35.0	32.0	29.5
Wealth quintile
Poorest	21,425	46.9	42.5	48.8	44.7
Middle	8,985	19.7	20.1	19.5	19.9
Richest	15,280	33.4	37.4	31.8	35.4
Wanted the pregnancy
Wanted then	39,191	89.4	84.8	89.5	90.4
Wanted later	2,899	6.6	9.5	5.7	7.6
Not at all	1,746	4.0	5.7	4.8	2.1
Number of previous pregnancies
None	8,540	17.4	18.6	17.1	17.5
1	7,171	16.0	15.5	16.2	15.7
2–3	12,384	27.5	26.2	27.5	27.9
4–6	11,640	25.9	25.3	25.9	26.1
7+	5,957	13.3	14.5	13.3	12.8
Total	45,690	100	9.1	42.3	48.6

Abbreviations: LWSP, living with sexual partner; DHS, Demographic and Health Survey.

Table 2 Prevalence of ANC utilization and proportion who started ANC visits during first trimester by women characteristics

Characteristics	% who accessed ANC				% of users starting ANC in first trimester
	2003	2008	2013	All	2003	2008	2013	All
Age, years
15–19	53.7	44.9	54.1	48.6*	26.9	29.2	26.5	28.0
20–24	62.0	56.7	63.2	59.3*	30.3	33.9	33.2	33.3*
25–34	68.6	64.7	68.0	66.1*	33.7	33.3	33.5	33.4
35–49	67.8	59.9	65.7	62.4*	34.9	29.7	30.9	30.5*
Mother education
No education	43.0	34.6	42.1	37.7*	30.4	30.1	26.7	28.9*
Primary	82.2	76.4	77.3	77.2*	31.2	30.4	31.7	30.9*
Secondary	93.7	90.6	89.8	90.5*	35.8	33.3	34.7	34.0*
Higher	98.7	98.3	98.8	98.5	40.0	41.3	42.7	41.7
Marital status
Never	86.7	75.4	78.9	77.5	37.8	25.2	28.6	27.6*
Married/LWSP	65.0	59.9	64.9	62.0*	33.1	32.5	32.5	32.6*
Formerly married	72.6	67.8	73.4	70.2	24.0	31.9	31.2	30.8
Religion
Islam	89.6	43.6	53.8	48.4*	39.0	29.5	28.2	29.4*
Xtian	88.4	83.3	83.4	83.6*	34.4	34.2	36.4	34.9*
Others	51.8	46.9	51.9	50.8	29.4	29.7	30.9	29.6
Tribe
Hausa/Fulani	43.6	31.6	44.5	37.1*	25.9	26.4	22.4	24.6*
Yoruba	96.7	94.9	97.2	95.8*	41.4	29.6	35.8	32.6*
Igbo	95.7	91.1	95.7	96.0*	34.8	35.6	37.8	36.3*
Others	66.2	68.6	70.6	69.0*	32.3	34.6	35.7	34.7*
Involved in her income spending
Yes	69.6	65.4	69.1	67.2*	34.9	32.4	32.6	32.7*
No	80.2	60.7	71.1	64.9*	37.0	38.5	32.5	36.5*
Involved in her health care decision
Yes	81.6	76.8	80.6	78.3*	37.8	32.6	36.4	34.1*
No	61.1	48.3	56.0	52.3*	30.8	32.3	29.4	31.1*
Residence
Urban	85.0	86.1	88.9	87.1*	33.5	31.0	30.8	31.2*
Rural	55.6	51.2	54.0	52.4*	32.4	33.0	33.6	33.2*
Zone
North Central	75.2	73.8	78.8	75.4*	45.3	41.2	45.0	42.7*
North East	53.2	48.6	61.1	52.9*	29.0	32.1	32.0	31.8*
North West	44.1	27.5	42.2	34.4*	20.5	23.2	19.5	21.2*
South East	98.2	90.3	95.6	92.7*	33.4	34.9	37.8	35.7*
South South	85.1	80.4	70.9	77.5*	33.9	32.1	28.8	31.2*
South West	97.6	94.5	92.5	94.1*	37.3	26.5	34.3	29.9*
Distance to health facility is a problem
Big problem	49.2	50.6	46.4	49.3*	31.3	32.3	29.6	31.5*
No problem	71.7	67.2	74.8	70.3*	33.2	32.2	33.2	32.7*
Working
Yes	71.4	65.4	69.9	67.4*	34.8	33.0	33.0	33.1*
No	55.3	49.8	54.9	51.9*	28.2	30.1	30.3	30.0
Wealth quintile
Poorest	45.6	37.4	42.0	39.5*	31.3	30.9	30.6	30.8
Middle	66.6	71.3	74.5	72.0*	31.2	32.4	32.9	32.4*
Richest	90.4	90.8	91.5	91.0	34.6	33.1	33.3	33.3*
Wanted the pregnancy
Wanted then	63.6	59.3	64.1	61.3*	32.9	32.5	32.3	32.5*
Wanted later	75.5	70.0	79.8	74.4*	34.0	33.7	34.0	33.8
Not at all	83.3	73.6	80.9	76.0*	31.5	26.9	28.2	27.7
Number of previous pregnancies
None	72.3	66.5	72.7	69.1*	36.0	32.0	33.2	32.8*
1	69.6	65.2	70.7	67.3*	34.7	38.1	37.1	37.5
2–3	68.0	63.9	68.4	65.7*	33.2	31.7	33.3	32.4*
4–6	62.3	58.5	62.7	60.2*	30.1	30.4	30.1	30.3*
7+	57.6	45.5	51.1	48.4*	31.0	28.4	26.0	27.9
Total	65.8	60.5	65.5	62.6*	32.9	32.2	32.4	32.3*

Note:

* Significantly different across DHS years at 5%.

Abbreviations: ANC, antenatal care; DHS, Demographic and Health Survey; LWSP, living with sexual partner.

Table 3 The incidence rate, median survival time, and log-rank test of timing of first ANC visit by selected characteristics and survey years

Characteristics	Incidence rate				Median survival time (months)
	2003	2008	2013	All	2003	2008	2013	All
Age, years
15–19	0.07	0.06	0.07	0.06	9	a	a	a
20–24	0.10	0.09	0.11	0.10	6	6	6	6*
25–34	0.12	0.11	0.12	0.12	5	6	5	5
35–49	0.11	0.09	0.11	0.10	6	6	6	6
Mother education
No education	0.06	0.05	0.06	0.06	a	a	a	a
Primary	0.15	0.13	0.14	0.14	5	5	5	5*
Secondary	0.18	0.17	0.17	0.17	4	5	5	5
Higher	0.20	0.21	0.21	0.21	4	4	4	4
Marital status
Never	0.12	0.10	0.11	0.11	6	6	6	6*
Formerly married	0.11	0.10	0.11	0.10	6	6	6	6
Married/LWSP	0.12	0.11	0.13	0.12	6	6	5	5
Religion
Islam	0.17	0.06	0.08	0.08	5	a	7	8*
Xtian	0.16	0.15	0.16	0.16	5	5	5	5
Others	0.08	0.07	0.08	0.08	7	a	7	7
Tribe
Hausa/Fulani	0.06	0.04	0.06	0.05	a	a	a	a
Yoruba	0.21	0.19	0.21	0.20	4	5	4	4*
Igbo	0.18	0.18	0.20	0.19	5	5	4	4
Others	0.11	0.12	0.12	0.12	6	5	5	5
Involved in her income spending
Yes	0.12	0.11	0.12	0.12	5	6	5	5
No	0.14	0.10	0.12	0.11	5	6	5	5
Involved in her health care decision
Yes	0.15	0.14	0.15	0.15	5	5	5	5*
No	0.10	0.07	0.09	0.08	6	a	7	7
Residence
Urban	0.16	0.17	0.17	0.17	5	5	5	5*
Rural	0.09	0.08	0.09	0.08	7	8	7	7
Zone
North Central	0.14	0.13	0.15	0.14	5	5	5	5*
North East	0.08	0.07	0.10	0.09	7	a	6	7
North West	0.06	0.04	0.06	0.05
South East	0.19	0.17	0.20	0.19	5	5	4	4
South South	0.14	0.14	0.12	0.13	5	5	6	5
South West	0.20	0.19	0.19	0.19	4	5	4	5
Distance to health facility is big problem
Big problem	0.07	0.08	0.07	0.07	a	8	a	a
No problem	0.12	0.11	0.13	0.12	5	5	5	5
Working
Yes	0.13	0.11	0.12	0.12	5	6	5	5*
No	0.08	0.07	0.09	0.08	7	a	7	7
Wealth quintile
Poorest	0.07	0.05	0.06	0.06	a	a	a	a
Middle	0.11	0.12	0.13	0.12	6	5	5	5*
Richest	0.17	0.18	0.18	0.18	5	5	4	5
Wanted the pregnancy
Wanted then	0.11	0.10	0.11	0.10	6	6	6	6*
Wanted later	0.13	0.12	0.15	0.14	5	5	5	5
Not at all	0.14	0.13	0.15	0.13	5	5	5	5
Previous pregnancies
None	0.10	0.09	0.11	0.09	6	7	6	6*
1	0.13	0.11	0.13	0.12	5	5	5	5
2–3	0.12	0.11	0.12	0.12	5	6	5	5
4–6	0.11	0.09	0.11	0.10	6	6	6	6
7+	0.09	0.07	0.08	0.08	6	a	7	8
Total	0.11	0.10	0.11	0.10	6	6	6	6

Notes: a: median survival time cannot be computed.

* Significantly different at 5% log-rank test.

Abbreviations: ANC, antenatal care; LWSP, living with sexual partner.

Table 4 The adjusted risk factors of timing of first ANC visit by selected characteristics and survey years

Characteristics	Adjusted hazard ratios (95% CI)
	2003	2008	2013	All women
DHS
2008				Reference
2003				1.19 (1.12–1.26)
2013				1.08 (1.06–1.11)
Age, years
15–19	Reference
20–24	1.06 (0.88–1.27)	1.16 (1.04–1.29)	1.19 (1.08–1.31)	1.16 (1.09–1.24)
25–34	1.18 (0.97–1.44)	1.18 (1.06–1.31)	1.21 (1.10–1.34)	1.20 (1.12–1.29)
35–49	1.18 (0.94–1.48)	1.15 (1.01–1.30)	1.24 (1.11–1.38)	1.19 (1.11–1.29)
Mother education
No education	Reference
Primary	1.61 (1.43–1.81)	1.72 (1.62–1.83)	1.61 (1.52–1.70)	1.67 (1.6–1.74)
Secondary	1.71 (1.49–1.95)	1.86 (1.74–2.00)	1.76 (1.65–1.87)	1.82 (1.74–1.9)
Higher	1.75 (1.42–2.15)	2.04 (1.86–2.25)	1.97 (1.81–2.14)	1.99 (1.87–2.11)
Marital status
Never	Reference
Formerly married	1.00 (0.78–1.28)	1.10 (0.99–1.22)	1.04 (0.94–1.15)	1.02 (0.82–1.27)
Married/LWSP	0.90 (0.74–1.10)	1.14 (1.03–1.27)	1.15 (1.05–1.26)	0.89 (0.74–1.09)
Religion
Islam	Reference
Xtian	1.02 (0.89–1.16)	1.09 (1.03–1.16)	0.99 (0.94–1.05)	1.02 (0.99–1.06)
Others	0.82 (0.72–0.95)	0.94 (0.81–1.09)	0.80 (0.67–0.94)	0.84 (0.79–0.90)
Tribe
Hausa/Fulani	Reference
Yoruba	1.17 (0.94–1.47)	1.21 (1.08–1.35)	1.19 (1.08–1.31)	1.19 (1.11–1.27)
Igbo	1.17 (0.92–1.5)	1.27 (1.11–1.45)	1.25 (1.11–1.40)	1.25 (1.15–1.36)
Others	1.23 (1.06–1.41)	1.26 (1.16–1.36)	1.14 (1.06–1.22)	1.19 (1.14–1.25)
Involved in her income spending decision
	Reference
Yes	1.00 (0.84–1.18)	1.09 (1.01–1.18)	1.06 (0.98–1.14)	1.07 (1.02–1.13)
No
Involved in her health care decision
Yes	1.07 (0.97–1.18)	1.08 (1.03–1.12)	1.02 (0.98–1.06)	1.05 (1.02–1.08)
Residence
Urban	1.16 (1.06–1.28)	1.13 (1.08–1.19)	1.08 (1.03–1.13)	1.11 (1.08–1.15)
Zone
North Central	1.48 (1.26–1.74)	2.15 (1.96–2.35)	1.59 (1.47–1.72)	1.76 (1.67–1.86)
North East	1.17 (1.01–1.35)	1.81 (1.67–1.96)	1.63 (1.52–1.74)	1.60 (1.53–1.68)
North West	Reference
South East	1.5 (1.15–1.95)	1.91 (1.66–2.21)	1.64 (1.45–1.86)	1.69 (1.55–1.85)
South South	1.11 (0.91–1.35)	1.54 (1.39–1.71)	0.96 (0.88–1.05)	1.16 (1.08–1.23)
South West	1.56 (1.26–1.95)	1.87 (1.66–2.1)	1.36 (1.24–1.50)	1.54 (1.44–1.65)
Distance to health facility is big problem
Big problem	1.23 (1.10–1.38)	1.21 (1.15–1.26)	1.44 (1.38–1.51)	1.31 (1.27–1.35)
Working
Yes	1.21 (1.10–1.33)	1.11 (1.06–1.17)	1.19 (1.14–1.24)	1.16 (1.13–1.20)
Wealth quintile
Poorest	Reference
Middle	1.49 (1.32–1.68)	1.67 (1.57–1.77)	1.55 (1.47–1.64)	1.57 (1.52–1.64)
Richest	1.76 (1.56–1.99)	1.86 (1.74–1.98)	1.64 (1.54–1.74)	1.71 (1.64–1.78)
Wanted the pregnancy
Wanted then	Reference
Wanted later	0.98 (0.86–1.11)	0.97 (0.89–1.05)	1.04 (0.97–1.11)	0.99 (0.95–1.04)
Not at all	0.99 (0.83–1.17)	0.86 (0.78–0.95)	0.96 (0.86–1.06)	0.93 (0.87–0.99)
Previous pregnancies
None	Reference
1	1.34 (1.16–1.55)	1.28 (1.19–1.37)	1.26 (1.18–1.35)	1.27 (1.22–1.33)
2–3	1.18 (1.01–1.36)	1.19 (1.11–1.28)	1.16 (1.09–1.24)	1.17 (1.12–1.23)
4–6	1.07 (0.90–1.26)	1.21 (1.11–1.31)	1.14 (1.06–1.23)	1.15 (1.09–1.22)
7+	1.22 (0.99–1.50)	1.13 (1.01–1.25)	1.04 (0.95–1.15)	1.10 (1.03–1.17)

Abbreviations: ANC, antenatal care; DHS, Demographic and Health Survey; LWSP, living with sexual partner.

Figure 1 Proportion attending ANC and proportion who started in the first trimester by survey years.

Abbreviations: ANC, antenatal care; DHS, Demographic and Health Survey.

Figure 2 Percentage and cumulative percentage distribution of the month of ANC initiation by survey years.

Note: *Cumulative probability distribution.
Abbreviation: ANC, antenatal care.

Figure 3 Survival functions of first ANC visit by survey years and respondent characteristics.

Abbreviation: ANC, antenatal care.