TABLE 1.

Characteristics of included studies.

Study	Methods	Participants	Intervention	Outcomes	Quality score
Azhari et al. 2006	Randomised controlled trial	Primi and multigravid, pregnant females, age 19–35 years, gestational age 40–42 weeks, singleton pregnancies, Bishop’s score less than or equal to four, intact membranes, reactive non-stress test	Castor oil, 60 mL, orally	Initiation of labour with onset of three strong uterine contractions	I B
Ensiyeh & Sakineh 2009	Double-blind randomised controlled trial	Primi and multigravid, pregnant females, aged 20–30, at 17 weeks of gestation or less who experienced nausea with or without vomiting	Ginger, 1 g/day for 4 days, orally	Changes in severity of nausea	I A
Garry et al. 2000	Controlled trial	Mean age of 24.5, at 40–42 weeks’ gestation, Bishop’s score of 4 or less, no evidence of uterine contractions on tocometry	Castor oil, 60 mL, orally	Onset of labour in 24 hours; 1 or more contractions every 5 minutes with cervical dilation of 4 cm or more	II B
Gilad et al. 2012	Randomised, double-blind, placebo-controlled trial	Singleton pregnancy, 40–42 weeks, Bishop’s score less than or equal to 7, no uterine activity and no previous caesarean section	Castor oil, 60 mL, orally	Spontaneous onset of labour within 12 hours	I A
Keating & Chez 2002	Double-blind randomised controlled trial	Primi and multigravid, pregnant females, aged 24–37 years in the first trimester (7–11 weeks of gestation), experiencing nausea and/or without vomiting, and were not taking a prescribed or over the counter antiemetic	Ginger syrup 250 mg ginger (1 tablespoon), 4× daily orally	Level of nausea	I B
Smith et al. 2004	Randomised, controlled equivalence trial	Women with nausea or vomiting, between 8 and 16 weeks pregnant, with dates confirmed by ultrasound	Ginger; 1 capsule of ginger (350 mg), orally	Nausea	II B
Vutyavanich, Kraisarin & Ruangsri 2001	Randomised, double-masked, placebo-controlled trial	Women with nausea of pregnancy, with or without vomiting, at or before 17 weeks gestation	Ginger; 1 g in 250 mg capsule, orally	Improvement in nausea symptoms	I B
Willetts, Ekangaki & Eden 2003	Double-blind randomised placebo-controlled trial	Pregnant women aged 22–43 years, less than 20 weeks pregnant, had experienced morning sickness daily for at least a week which had failed to respond to dietary measures	125 mg ginger extract (equivalent to 1.5 g of dried ginger) orally	Nausea	I A