(c).

A: inclusion	Whether the paper identified the systematic review was included in the meta-analysis	0	Yes
		1	Excluded in the first stage
		2	Excluded in the second stage
A: study design		CS	Cross-sectional
		PC	Prospective cohort
		RCT	Randomised controlled trials
A: ethnicity	The percentages of White, Black, and Hispanic women in the sample are given where available	B	Black
		W	White
		H	Hispanic
	Where no information was given on ethnicity, the country in which the participants were recruited is given. Note that the percentages do not always add to 100%, this is due to different “other” categories
A: statistic	Whether the data were summarized using an OR or CC or both	OR	Odds ratio
		CC	Correlation coefficient
A: outcome	Whether the outcome was measured as gestational age (GA) in weeks or as a binary PTB or SPTB	PTB SPTB	(Spontaneous) preterm birth < 37 weeks (w); GA unless otherwise stated Spontaneous preterm birth < 37 weeks GA unless otherwise stated
B: PPV	The primary predictor variable (i.e., the type of anxiety)	Anxiety	General or not otherwise specified
		Trait	Trait anxiety
		State	State anxiety
		PSA	Pregnancy specific anxiety
		AD	Anxiety disorder
B: scale	The scale used to measure the type of anxiety  ∗Indicates adapted (e.g., some items were omitted such as somatic complaints) Wadhwa∗, Rini∗, Dunkell-Schetter∗, Lukesch∗ all refer to PSA scales adapted from those designed by these original authors	HADS –A	Hospital anxiety and depression rating scale, anxiety
		STPI	State-trait personality inventory
		STAI (-T, -Y, -6)	The Spielberger sate and trait anxiety scale and various versions of this
		PSIS	Prenatal social inventory scale (Orr)
		PSEI	Prenatal social environment inventory
		GHQ	General health questionnaire
		PAIP	Psychosocial adaptation in pregnancy
		GAD-7	Generalized anxiety disorder
		DASS-21	Depression and anxiety stress scale
		CAI	Chernobyl anxiety index
		PRIME - MD	Primary care evaluation of mental disorders
		RD	Researcher developed
		SCID	Structured clinical interview of DSM-IV disorders
B: # items	The number of items in the scale
B: scale	The scoring for each item		1_4 indicates 1, 2, 3, or 4
B: range	Where possible the limits of the range are given, for example, 20–80. Otherwise the width of the range is given
B: cut-off	The cut-point at which the scales was divided to indicate low compared with high anxiety	N	Not clear whether the cut-point is > or ≥N
		≥N
		C	The scale was used in as a continuous variable and no cut-off was used
		Q	The quartiles from the sample were used to define cut-points but were not always specified
		B	The anxiety disorder has been determined by diagnosis
B: # Obs.	Number of observations indicate the number of times that the PPV was measured during pregnancy
B: times	The times during pregnancy that the measurement was taken		Booking (b); weeks (w)
B: MMM	The method of the author used to deal with the multiple measurements	First	The first measurement was used
		Mean	The mean of all 3 scores was taken
		Both	Both variables were included simultaneously in the model
		Max	Maximum value at any point during a particular woman's pregnancy
		3 CC	Three correlation coefficients were calculated
B: trimester	The trimester(s) in which most of the measures in each study were probably taken Derived from the times	1	First
		2	Second
		3	Third
		E	Early
		L	Late