Table 1. Some general characteristics of research subjects

Characteristics		Amount	Percentage
Accommodation	HCM City	160	90%
	Other regions	18	10%
Participants age	18-24	14	8%
	25-34	143	80%
	35-45	21	12%
	Over 45	0	0%
Duration of pregnancy	First trimester	10	6%
	Second trimester	162	91%
	Third trimester	6	3%
Pregnancy feature	Singleton pregnancies	172	97%
	Twin pregnancies	6	3%
Total		178	100%