Table 10.

Summary of the outcome of studies on birth length in which exposure was used as categorical variable

Reference	Study design	Exposure	Timing of exposure/assessment	Com‐pound	Unit	Exposure high	Exposure low	n expos. high	n expos. low	n total	Mean difference (cm) (95% CI)	Ad‐justed
Shahraki et al. (2016)	RCT	Supple‐mentation	From 4–16 gw onwards	Pyridoxine HCl	mg/day	40	Ondan‐setron	100	88	188	0.5 (0.07, 0.93)	No
Schuster et al. (1984)	RCT	Supple‐mentation	From 6–21 gw onwards	Pyridoxine HCl	mg/day	7.5–20	0–5	112	84	196	−0.2 (−0.88, 0.48)	No
Chang (1999)	CS	Cord blood	Birth	PLP	nmol/L	≥ 50	< 40	NR	NR	209	2 (1.3, 2.7)	No

CI: confidence interval; CS: cross‐sectional study; expos.: exposure; gw: gestational weeks; HCl: hydrochloride; NR: not reported; PLP: pyridoxal phosphate; RCT: randomised controlled trial.