Table 1 Overview of demographics and pregnancy outcomes with their definitions

Lifestyle Behaviours

(Self-reported in the first trimester)

Body mass index

Kg/m²

Underweight

<18.5 kg/m²

Normal weight

18.5 - 25 kg/m²

Overweight

25-30 kg/m²

Obese

>30 kg/m²

Daily fruit intake

Pieces of fruit

Not-adequate

< 2 pieces

Adequate

≥ 2 pieces

Tobacco use

≥1 cigarette per day (yes/no)

Alcohol use

≥1 glass of alcohol per week (yes/no)

Folic acid use

Use of folic acid, either as a single supplement or as part of multivitamin preparation (yes/no)

Vitamin use

Use of vitamin C, vitamin D or calcium supplement either as a single supplement or as part of multivitamin preparation (yes/no)

Socio-demographic characteristics

(Self-reported in the first trimester)

Age

Years

Ethnicity

- White: Caucasian or other Western;

- Non-White: African, Hindustani, Moroccan, Turkish, Middle Eastern, Asian, other non-western, and mixed.

Educational level

- Low: primary education or lower level;

- Medium: secondary education;

- High: tertiary education or higher level.

Parity

- Nulliparous: women with no previous pregnancies beyond 16 weeks;

- Multiparous: women with previous pregnancies beyond 16 weeks.

Mode of conception

- Spontaneous conception: pregnant without medical assistance;

- Non-spontaneous conception: pregnant with ovulation drugs, insemination or in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI).

Adverse pregnancy outcomes

(Reported by the healthcare provider after the pregnancy)

Hypertensive disorder in pregnancy (HDP)

Either:

- Pregnancy-induced hypertension (PIH): the new onset of hypertension (≥ 140 mmHg systolic and/or ≥90 mmHg diastolic blood pressure) after 20 weeks gestation measured on at least two occasions four hours apart;

- Pre-eclampsia (PE): PIH accompanied by proteinuria (≥300 mg in 24 hours), either during pregnancy or postpartum [24, 25, 26].

Small for gestation age (SGA)

A birth weight <3rd percentile, based on Hoftiezer percentiles [27, 28].

Gestational diabetes (GDM)

The presence of either a fasting glucose level of ≥7.0 mmol/L (126 mg/dl) or a glucose level of ≥7.8 mmol/L (140 mg/dl) two hours after a 75-grams oral glucose tolerance test [29,30,31].

Spontaneous preterm birth (sPTB)

A delivery with spontaneous onset before 37 weeks of gestation [32].

Composite outcome

Women with one of the following complications; pregnancy-induced hypertension, pre-eclampsia, small for gestational age <p3, gestational diabetes, spontaneous preterm birth or fetal death.