. 2023 Jan 28;42(1):4. doi: 10.1007/s11113-023-09759-1

Table 3.

Robustness tests

Variable	(1)	(2)	(3)	(4)	(5)
Variable	Narrow gestational period	Narrow birth month range [1]	Narrow birth month range [2]	Logged dependent variable	Clustering by region and month
$T_{it}^{1}$	− 2.829	− 3.056	− 2.186	− 0.001	− 3.036
$T_{it}^{1}$	(2.060)	(1.929)	(2.402)	(0.001)	(2.201)
$T_{it}^{2}$	− 20.116**	− 9.896**	− 8.422**	− 0.006**	− 19.776**
$T_{it}^{2}$	(2.787)	(2.719)	(3.134)	(0.001)	(2.287)
$T_{it}^{1}$ $\times$ $T_{it}^{2}$	5.174*	8.045**	9.439*	0.002**	6.547*
$T_{it}^{1}$ $\times$ $T_{it}^{2}$	(2.481)	(2.766)	(4.172)	(0.001)	(2.625)
Female	− 113.507**	− 113.551**	− 112.265**	− 0.035**	− 112.658**
Female	(1.151)	(1.382)	(1.960)	(0.000)	(1.141)
Birth in a clinic	25.978**	24.708*	29.669 +	0.005 +	16.260 +
Birth in a clinic	(9.981)	(11.707)	(17.168)	(0.003)	(8.436)
Birth after marriage	30.077**	22.954**	26.405**	0.010**	29.955**
Birth after marriage	(5.124)	(6.137)	(8.687)	(0.001)	(3.979)
Birth within 2 years	− 7.172**	− 7.413**	− 6.334*	− 0.003**	− 8.467**
Birth within 2 years	(1.448)	(1.739)	(2.471)	(0.000)	(1.395)
Total births	44.324**	47.198**	48.545**	0.015**	47.834**
Total births	(1.126)	(1.328)	(1.888)	(0.000)	(1.224)
Father’s schooling	7.239**	10.115**	11.311**	0.003**	9.340**
Father’s schooling	(1.610)	(1.932)	(2.726)	(0.000)	(1.342)
Mother’s schooling	4.720**	7.641**	5.813 +	0.002**	6.716**
Mother’s schooling	(1.763)	(2.102)	(2.988)	(0.001)	(1.477)
Father’s age	− 0.504	− 0.453	0.472	− 0.000	− 1.012
Father’s age	(1.245)	(1.493)	(2.143)	(0.000)	(1.247)
Father’s age squared	0.004	0.005	-0.007	0.000	0.010
Father’s age squared	(0.017)	(0.020)	(0.029)	(0.000)	(0.016)
Mother’s age	13.422**	14.013**	16.370**	0.004**	14.079**
Mother’s age	(1.636)	(1.976)	(2.807)	(0.000)	(1.542)
Mother’s age squared	− 0.181**	− 0.190**	− 0.228**	− 0.000**	− 0.190**
Mother’s age squared	(0.025)	(0.030)	(0.043)	(0.000)	(0.023)
Birth month FE	Y	Y	Y	Y	Y
Birth region FE	Y	Y	Y	Y	Y
Gestational period FE	Y	Y	Y	Y	Y
R²	0.071	0.105	0.104	0.109	0.105
N	372,932	266,183	132,523	434,355	434,355

We limited the sample to those whose gestational period was between 38 and 40 weeks in column (1). We limited the sample to those whose birth months were from January to June in column (2). We limited the sample to those whose birth months were from February to April in column (3). The dependent variable is the log-transformed birth weight in column (4). Column (5) shows the estimation results when clustering standard errors at the month-region level

Robust standard errors in parentheses, + p < 0.10, *p < 0.05, **p < 0.01