Table 1.

Unweighted characteristics of children $<5$ years of age by four quartiles of 9-month in utero ${\mathrm{PM}}_{2.5}$ exposure who were born between 2010–2016 in the Demographic and Health Surveys [DHS, also known as the National Family Health Survey 2015–2016 (NFHS-4)] in India.

Characteristics	Entire cohort	Average 9-month in utero ${\mathrm{PM}}_{2.5}$ exposure quartile (${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$) (Q)
		Q1 ($20.9–<49.7$)	Q2 ($49.7–<62.4$)	Q3 ($62.4–<90.3$)	Q4 (90.3–153.5)
Average 9-month in utero ${\mathrm{PM}}_{2.5}$ exposure (${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$)
Children ($n$)	252,788	63,197	63,197	63,197	63,197
Total follow-up in month ($n$)	7,447,724	1,860,527	1,891,613	1,873,198	1,822,386
Child death at $<5$ years of age ($n$)	11,559	2,187	2,688	3,001	3,683
All-cause child mortality rate ($n$/1,000 child-years)	18.62	14.11	17.05	19.22	24.25
Average 9-month in utero ${\mathrm{PM}}_{2.5}$ {${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ [mean (SD)]}	71.1 (28.2)	41.4 (6.0)	55.4 (3.6)	75.0 (8.1)	112.6 (13.9)
Average post-delivery lifetime ${\mathrm{PM}}_{2.5}$ exposure until death or censoring {${\mathrm{\mu }\mathrm{g}/\mathrm{m}}^3$ [mean (SD)]}	73.7 (29.8)	46.6 (10.6)	57.1 (11.5)	83.6 (25.6)	107.6 (20.1)
Child covariatesa
Sex (%)
Female	47.9	48.4	47.8	47.6	47.3
Male	52.1	51.6	52.1	52.4	52.6
LBW (%)b	13.1	14.2	13.4	13.9	11.2
Birth order (%)
First	36.9	40.8	38.0	37.1	31.5
Second	30.7	34.2	31.1	30.0	27.5
Third	16.1	14.2	15.7	16.4	18.1
$\ge \text{Fourth}$	16.3	10.8	15.2	16.5	22.9
Multiple birth (%)	1.65	1.55	1.53	1.81	1.71
Birth at institution (%)	75.3	81.8	75.7	74.8	68.7
Maternal covariatesa
Age at child birth [y (%)]
$<19$	12.2	12.6	11.3	12.9	11.8
20–24	43.4	43.4	42.2	44.5	43.4
25–29	28.4	28.6	29.2	27.8	28.3
$\ge 30$	16.0	15.4	17.5	14.8	16.5
Mothers height [cm (%)]
$<149.9$	38.3	34.2	34.0	37.5	47.4
150–154.9	33.8	35.3	34.6	33.3	32.2
155–159.9	19.7	21.5	21.9	20.4	15.0
$>160$	8.2	9.0	9.5	8.8	5.4
Marital status (%)
Not married	1.4	1.9	1.8	1.1	0.9
Married	98.6	98.1	98.2	98.9	99.1
Education (%)
Below secondary level	31.5	19.4	27.3	34.8	44.3
Above secondary level	68.5	81.6	72.7	66.2	55.7
Current smoker (%)	10.0	13.4	14.0	7.5	5.2
Secondhand smoke exposure (%)	56.6	51.8	60.5	56.5	58.3
Household covariatesa
Cook with clean fuel (%)	27.8	38.5	28.4	23.1	21.1
Access to improved toilet (%)	41.5	48.0	44.7	39.3	33.9
Urban/Rural (%)
Urban area	23.6	29.2	23.3	22.1	19.9
Rural area	76.4	70.8	76.7	77.9	80.1
Zone area (%)
Northern	16.6	3.5	25.7	29.4	7.9
North Eastern	13.8	20.9	23.9	9.8	0.5
Central	31.8	18.6	31.2	27.2	50.3
Eastern	21.1	5.0	9.6	28.5	41.3
Western	7.1	14.5	8.7	5.1	0
Southern	9.6	37.5	0.9	0	0
Wealth quartiles (%)c
First (lowest)	25	15.6	21.7	27.1	35.6
Second	25	23.4	26.3	24.5	25.9
Third	25	31.3	26.4	22.4	19.8
Forth	25	29.7	25.6	26.0	18.7
Meteorological covariatesd
Temperature {°C [mean (SD)]}	27.1 (6.4)	26.7 (4.9)	24.7 (7.8)	27.6 (6.0)	29.4 (5.5)
Total rainfall {cm [mean (SD)]}	103 (144)	115 (144)	98 (134)	90 (145)	110 (151)

Note: LBW, low birth weight; ${\mathrm{PM}}_{2.5}$, particulate matter $\le 2.5\mathrm{\mu }\mathrm{m}$ in aerodynamic diameter (fine particulate matter); SD, standard deviation.

^a Child, maternal and household-level covariates collected at the end of the follow-up during the DHS/NFHS-4 interview between 2015–2016.

^b Assuming children with missing LBW values are not LBW infants.

^c The household wealth index developed by the DHS/NHFS-4 was calculated using principle component analysis of household ownership of assets.

^d Meteorological covariates were averaged post-delivery monthly estimates.