Table 1.

Characteristics of workload from workplace, hobbies, and household during pregnancy as reported via two questionnaires of the MT1 and MT2 in the Japan Environment and Children’s Study (JECS)

Variables	MT1		MT2		P
	N	%	N	%
I have been engaged in at least one of the following activities from nos. 1 to 7 after becoming pregnant
Yes	13,410	14.0	11,306	11.8	< 0.0001
No	82,070	86.0	84,174	88.2
1. Lifting objects that weigh more than 20 kg
Yes	5078	5.3	3744	3.9	< 0.0001
No	90,402	94.7	91,736	96.1
2. Exposed to loud noise
Yes	3353	3.5	3597	3.8	< 0.0001
No	92,127	96.5	91,883	96.2
3. Going in and out of commercial refrigerator or freezer
Yes	2646	2.8	2091	2.2	< 0.0001
No	92,834	97.2	93,389	97.8
4. Working in a hot place that makes one sweat
Yes	1841	1.9	1719	1.8	0.0078
No	93,639	98.1	93,761	98.2
5. Using organic solvent
Yes	1508	1.6	1583	1.7	0.0288
No	93,972	98.4	93,897	98.3
6. Handling powder dust
Yes	810	0.8	850	0.9	0.1211
No	94,670	99.2	94,630	99.1
7. Using manufacturing tools with vibration
Yes	417	0.4	565	0.6	< 0.0001
No	95,063	99.6	94,915	99.4

P values are by McNemar test. The questionnaire intended to be administered during the first trimester (MT1) and that during the second/third trimester (MT2)

N number of valid responses