Table 2.

Identified characteristics and variables from NuMom2B dataset

Characteristics	Variables
Basic Preconception Characteristics	maternal age, history of cervical excisional procedures/surgery(Loop Electrosurgical Excision Procedure (LEEP)/conization), height, Body Mass Index(BMI), use of assisted reproductive technologies, family disease history(pregnancy complications and hypertension), and family history of preterm birth
Socio-Demographic Characteristics	socio-economic status, educational attainment, marital status, and ethnicity
Lifestyle Characteristics	tobacco use, alcohol use, mental stress, and maternal Vitamin-D deficiency
Obstetric/Pregnancy Characteristics	gestational diabetes, gestational hypertension, vaginal bleeding, serial transvaginal cervical length, and cervical insufficiency
Medical History Characteristics	pre-pregnancy diabetes history, pre-pregnancy hypertension history and obstetric history