The effects of pregnancy spacing on infant and child mortality in Matlab, Bangladesh: How they vary by the type of pregnancy outcome that began the interval

Figures & data

Table 1  Frequency distribution (per cent) of durations of inter-outcome intervals (by type of outcome that began the interval) and interbirth intervals. Matlab, Bangladesh, 1982–2002 (n = 125,720).¹ (Numbers in parentheses are the percentages of the row totals)

	Inter-outcome intervals							Interbirth intervals
	Type of pregnancy outcome at the beginning of the interval
Interval duration (months)	Live birth, child survived (lba)	Live birth, child died (lbd)	Stillbirth (sb)	Miscarriage (m)	Induced abortion (ia)	Total	Total as % of all intervals of known duration
<15	0.54 (9.2)	1.87 (31.7)	0.90 (15.3)	2.17 (36.8)	0.42 (7.1)	5.90	9.80	4.26
15–17	0.71 (28.4)	0.79 (31.6)	0.28 (11.2)	0.58 (23.2)	0.14 (5.6)	2.50	4.15	2.69
18–23	4.38 (64.4)	1.35 (19.9)	0.34 (5.0)	0.53 (7.8)	0.34 (5.0)	6.80	11.29	10.27
24–35	16.09 (86.9)	1.52 (8.2)	0.29 (1.6)	0.40 (2.2)	0.22 (1.2)	18.52	30.77	31.94
36–59	17.04 (92.6)	0.81 (4.4)	0.17 (0.9)	0.24 (1.3)	0.17 (0.9)	18.41	30.59	34.66
60–83	5.24 (93.6)	0.21 (3.8)	0.04 (0.7)	0.06 (1.1)	0.05 (0.9)	5.60	9.29	11.11
84 +	2.25 (91.5)	0.12 (4.9)	0.02 (0.8)	0.04 (1.6)	0.03 (1.2)	2.46	4.10	5.08
Duration unknown						16.15
1st pregnancies						23.66
Total	46.25 (76.8)	6.67 (11.1)	2.04 (3.4)	4.02 (6.7)	1.37 (2.3)	(100.00)	100.00	100.00
^1The percentages shown in this table refer to the total sample and the case of early neonatal mortality. Numbers are slightly different for later periods of infancy and for childhood because children who died or women who moved out of the DSS area leave the sample and because a few previous children who were alive at the beginning of a previous period (lba) may have died by the time of the beginning of the at-risk period under consideration (lbd).
Source: Matlab DSS data.

Table 2(a)  Results of Cox proportional hazards models (relative risks (RR) and standard errors (SE)) of first-week mortality: interbirth vs. inter-outcome intervals, without and with controls for duration of gestation, and effects of inter-outcome intervals by type of preceding pregnancy outcome, without and with controls for other explanatory variables. Matlab, Bangladesh, 1982–2002 (n = 125,720)

	Interbirth intervals		Inter-outcome intervals				Inter-outcome intervals; interval effects differ by preceding outcome
	Only other control is for first parity				Duration of gestation also controlled				Other explanatory variables also controlled^1
	(1)		(2)		(3)		(4)		(5)
	RR	SE	RR	SE	RR	SE	RR	SE	RR	SE
Interval duration (months) Outcome of previous pregnancy
<15	3.90	0.32****	2.62	0.19****	2.26	0.17****
Live birth alive (lba)							2.19	0.40****	2.11	0.39****
Live birth died (lbd)							3.79	0.34****	3.64	0.33****
Stillbirth (sb)							1.85	0.30****	1.87	0.30****
Miscarriage (m)							1.49	0.18***	1.48	0.18***
Induced abortion (ia)							1.04	0.29	1.05	0.30
15–17	1.77	0.24****	1.70	0.19****	1.51	0.17****
lba							1.80	0.32***	1.83	0.33***
lbd							1.41	0.28*	1.41	0.28*
Not a live birth (nlb)							1.46	0.25**	1.49	0.26**
18–23	1.50	0.13****	1.45	0.12****	1.26	0.10***
lba							1.25	0.12**	1.23	0.12**
lbd							1.62	0.23***	1.58	0.23***
nlb							1.21	0.22	1.21	0.22
24–35	1.07	0.07	1.06	0.07	0.94	0.06
lba							0.97	0.07	0.97	0.07
lbd							0.86	0.16	0.84	0.16
nlb							1.45	0.26**	1.47	0.26**
36–59 (RC)	1.00	(–)	1.00	(–)
lba (RC)					1.00	(–)	1.00	(–)	1.00	(–)
lbd							1.75	0.32***	1.71	0.31***
nlb							1.54	0.33**	1.55	0.34**
60–83	1.09	0.10	1.02	0.10	1.13	0.11
lba							1.17	0.12	1.15	0.12
Not lba							1.59	0.45*	1.56	0.44
84 +	1.34	0.15**	1.17	0.15	1.27	0.16*
lba							1.33	0.18**	1.29	0.18*
Not lba							1.45	0.55	1.37	0.52
Interval duration unknown	1.34	0.08****	1.34	0.09****	1.17	0.07**	1.23	0.08***	1.26	0.09***
1st birth	2.21	0.12
1st birth and 1st pregnancy			2.20	0.12****	2.15	0.12****	2.27	0.13****	2.07	0.14****
1st birth but not 1st pregnancy			1.15	0.11	1.27	0.12**	1.58	0.17****	1.54	0.17****
*p<0.10; **p<0.05; ***p<0.01; ****p<0.001; RC = reference category.
^1Full set of controls includes birth parity, mother's age, mother's education, father's education, father's presence, religion, household space size, month of birth, calendar year period, whether the mother lived in the MCH–FP Area, MCH–FP interacted with gestation unknown.
Source: As for Table 1.

Table 2(b)  Results of Cox proportional hazards models (relative risks (RR) and standard errors (SE)) of late neonatal mortality: interbirth vs. inter-outcome intervals, without and with controls for duration of gestation, and effects of inter-outcome intervals by type of preceding pregnancy outcome, without and with controls for other explanatory variables. Matlab, Bangladesh, 1982–2002 (n=121,936)

	Interbirth intervals		Inter-outcome intervals				Inter-outcome intervals; interval effects differ by preceding outcome
	Only other control is for first parity				Duration of gestation also controlled				Other explanatory variables also controlled^1
	(1)		(2)		(3)		(4)		(5)
	RR	SE	RR	SE	RR	SE	RR	SE	RR	SE
Interval duration (months) Outcome of previous pregnancy
<15	3.31	0.44****	2.40	0.28****	2.05	0.24****
Live birth alive (lba)							2.54	0.73***	2.45	0.70***
Live birth died (lbd)							3.09	0.45****	2.52	0.38****
Stillbirth (sb)							1.17	0.37	1.02	0.32
Miscarriage (m)							1.52	0.29**	1.41	0.27*
Induced abortion (ia)							1.80	0.61*	1.78	0.61*
15–17	2.02	0.38****	1.95	0.32****	1.71	0.28***
lba							1.42	0.44	1.34	0.42
lbd							2.37	0.55****	2.00	0.46***
Not a live birth (nlb)							1.49	0.40	1.38	0.37
18–23	1.74	0.21****	1.79	0.21****	1.53	0.18****
lba							1.47	0.20***	1.31	0.18*
lbd							1.93	0.39***	1.66	0.34**
nlb							1.67	0.42**	1.59	0.40*
24–35	1.62	0.15****	1.66	0.16****	1.42	0.13****
lba							1.54	0.15****	1.37	0.14***
lbd							1.31	0.30	1.13	0.26
nlb							0.96	0.33	0.96	0.33
36–59 (RC)	1.00	(–)	1.00	(–)
lba (RC)					1.00	(–)	1.00	(–)	1.00	(–)
lbd							1.62	0.46*	1.52	0.44
nlb							1.71	0.56	1.82	0.60*
60–83	0.72	0.12**	0.72	0.12*	0.81	0.14
lba							0.90	0.16	1.04	0.19
Not lba							0.30	0.30	0.34	0.34
84 +	0.93	0.19	0.92	0.20	1.02	0.22
lba							1.03	0.24	1.30	0.31
Not lba							1.46	0.85	1.76	1.03
Interval duration unknown	1.83	0.16****	1.88	0.18****	1.65	0.15****	1.73	0.17****	1.29	0.14**
1st birth	2.25	0.18****
1st birth and 1st pregnancy			2.38	0.20****	2.34	0.20****	2.46	0.22****	2.05	0.21****
1st birth but not 1st pregnancy			0.85	0.14	0.95	0.15	1.19	0.21	1.16	0.21
*p<0.10; **p<0.05; ***p<0.01; ****p<0.001.
^1See footnotes to Table 2(a).
Source: As for Table 1.

Table 2(c)  Results of Cox proportional hazards models (relative risks (RR) and standard errors (SE)) of post-neonatal mortality: interbirth vs. inter-outcome intervals, without and with controls for duration of gestation, and effects of inter-outcome intervals by type of preceding pregnancy outcome, without and with controls for other explanatory variables. Matlab, Bangladesh, 1982–2002 (n=119,718)

	Interbirth intervals		Inter-outcome intervals				Inter-outcome intervals; interval effects differ by preceding outcome
	Only other control is for first parity				Duration of gestation also controlled				Other explanatory variables also controlled^1
	(1)		(2)		(3)		(4)		(5)
	RR	SE	RR	SE	RR	SE	RR	SE	RR	SE
Interval duration (months) Outcome of previous pregnancy
<15	2.28	0.22****	1.87	0.15****	1.71	0.14****
Live birth alive (lba)							3.07	0.49****	3.14	0.51****
Live birth died (lbd)							1.89	0.22****	1.65	0.19****
Stillbirth (sb)							1.79	0.30***	1.53	0.26**
Miscarriage (m)							1.25	0.17*	1.14	0.15
Induced abortion (ia)							1.21	0.33	1.16	0.32
15–17	2.25	0.26****	2.05	0.21****	1.90	0.19****
lba							2.55	0.40****	2.54	0.40****
lbd							1.82	0.30****	1.61	0.27**
Not a live birth (nlb)							1.53	0.26**	1.41	0.24**
18–23	1.93	0.14****	1.91	0.14****	1.74	0.13****
lba							1.72	0.15****	1.56	0.13****
lbd							2.19	0.27****	1.88	0.23****
nlb							1.44	0.25**	1.33	0.23
24–35	1.33	0.08****	1.34	0.08****	1.22	0.07***
lba							1.23	0.08***	1.08	0.07
lbd							1.71	0.22****	1.43	0.18***
nlb							0.92	0.21	0.89	0.20
36–59 (RC)	1.00	(–)	1.00	(–)
lba (RC)					1.00	(–)	1.00	(–)	1.00	(–)
lbd							1.56	0.29**	1.39	0.26*
nlb							1.00	0.27	0.99	0.27
60–83	0.77	0.08**	0.71	0.08**	0.76	0.08**
lba							0.77	0.09**	0.86	0.10
Not lba							0.95	0.34	0.98	0.35
84 +	0.97	0.12	1.03	0.14	1.09	0.15
lba							1.08	0.15	1.28	0.19*
Not lba							1.58	0.56	1.79	0.64
Interval duration unknown	1.73	0.10****	1.77	0.10****	1.64	0.10****	1.68	0.10****	1.23	0.08***
1st birth	1.63	0.09****
1st birth and 1st pregnancy			1.69	0.09****	1.67	0.09****	1.71	0.10****	1.81	0.12****
1st birth but not 1st pregnancy			0.79	0.09**	0.84	0.10	1.01	0.13	1.22	0.16
*p<0.10; **p<0.05; ***p<0.01; ****p<0.001.
^1See footnotes to Table 2(a).
Source: As for Table 1.

Table 2(d)  Results of Cox proportional hazards models (relative risks (RR) and standard errors (SE)) of child mortality: interbirth vs. inter-outcome intervals, without and with controls for gestation, and effects of inter-outcome intervals by type of preceding pregnancy outcome, without and with controls for other explanatory variables (n=110,191). Matlab, Bangladesh, 1982–2002

	Interbirth intervals		Inter-outcome intervals				Inter-outcome intervals; interval effects differ by preceding outcome
	Only other control is for first parity				Duration of gestation also controlled				Other explanatory variables also controlled^1
	(1)		(2)		(3)		(4)		(5)
	RR	SE	RR	SE	RR	SE	RR	SE	RR	SE
Interval duration (months) Outcome of previous pregnancy
<15	1.40	0.17***	1.38	0.13****	1.29	0.12***
Live birth alive (lba)							1.57	0.38*	1.50	0.36*
Live birth died (lbd)							1.30	0.18*	1.05	0.14
Stillbirth (sb)							1.17	0.25	0.94	0.20
Miscarriage (m)							1.17	0.17	0.95	0.14
Induced abortion (ia)							1.55	0.40*	1.32	0.34
15–17	1.29	0.20*	1.28	0.16*	1.21	0.15
lba							2.02	0.38****	1.83	0.35***
lbd							0.68	0.18	0.54	0.14**
Not a live birth (nlb)							1.11	0.23	0.95	0.20
18–23	1.70	0.13****	1.65	0.13****	1.52	0.12****
lba							1.67	0.15****	1.41	0.13****
lbd							1.45	0.21**	1.10	0.16
nlb							0.96	0.21	0.83	0.18
24–35	1.54	0.09****	1.56	0.09****	1.44	0.09****
lba							1.46	0.09****	1.23	0.08***
lbd							1.53	0.20***	1.13	0.15
nlb							0.88	0.21	0.84	0.20
36–59 (RC)	1.00	(–)	1.00	(–)
lba (RC)					1.00	(–)	1.00	(–)	1.00	(–)
lbd							1.19	0.24	1.04	0.21
nlb							0.79	0.25	0.82	0.26
60–83	0.63	0.07****	0.67	0.08***	0.72	0.09***
lba							0.67	0.09***	0.75	0.10**
Not lba							1.43	0.44	1.54	0.47
84 +	0.72	0.12**	0.80	0.13	0.85	0.14
lba							0.92	0.16	1.10	0.19
Not lba							0.23	0.23	0.26	0.26
Interval duration unknown Subsequent pregnancy and birth in 1st year of index child's life	2.26	0.12****	2.38	0.14****	2.30	0.13****	2.30	0.14****	1.40	0.09****
Subsequent pregnancy									2.31	0.15****
Subsequent birth									1.34	0.49
1st birth	0.96	0.06
1st birth and 1st pregnancy			0.99	0.06	0.98	0.06	0.99	0.06	1.02	0.08
1st birth but not 1st pregnancy			0.61	0.09****	0.63	0.09***	0.72	0.11**	0.92	0.14
*p<0.10; **p<0.05; ***p<0.01; ****p<0.001.
^1See footnotes to Table 2(a).
Source: As for Table 1.

Figure 1  Interbirth intervals vs. inter-outcome intervals: how length of preceding interval affects mortality, without and with controls for duration of gestation. Matlab, Bangladesh, 1982–2002

Note: Open symbols indicate that the relative risk is not different from 1.0 at a significance level of p<0.05

Source: Table 2(a)–(d), Columns 1–3

Figure 2  Relative risks associated with inter-outcome intervals of various lengths (compared to intervals of 3–5 years following births of children who survived), by type of outcome of preceding pregnancy. Matlab, Bangladesh, 1982–2002

Note: Solid symbols indicate that relative risks are significantly different at p<0.05

Source: Table 2(a)–(d), Column 5