Prenatal Maternal Anxiety as a Risk Factor for Preterm Birth and the Effects of Heterogeneity on This Relationship: A Systematic Review and Meta-Analysis

Table 2

(a) Details of the studies in the systematic reviews inclusion in the meta-analysis. The table highlights the heterogeneity in terms of ethnicity, the type of statistic used to summarize the data, and the outcome variable. (b) Details of the primary predictor variable included in the studies (types of anxiety, measurement tool, number of items, scoring for each item, range of the total scale, number of times the predictor variable was measured during pregnancy, the method used by the authors’ to deal with multiple measures, and the trimester in which the measurements were most likely to be taken). (c) The key to the abbreviations.

(a)

Author	Year	Inclusion	Country	Study design	Ethnicity				Statistic	Outcome
					Ethnicity	W	H	B
Berle et al. [25]	2005	0	Norway	CS	Norway				OR	PTB
Copper et al. [29]	1996	2	USA	PC	B, W, H	35%	1%	63%	OR	SPTB (<35 w)
Dole et al. [31]	2004	0	USA	PC	B, W	62%		38%	OR	PTB: SPTB
Dominguez et al. [33]	2005	0	USA	PC	B			100%	CC	GA
Field et al. [34]	2010	0	USA	PC	B, W, H	9%	59%	32%	OR	PTB
Glynn et al. [35]	2008	0	USA	PC	B, W, H	48%	23%	14%	OR	PTB
Goldenberg et al. [19]	1996	1	USA	PC	B, W	31%	69%			PTB
Hosseini et al. [36]	2009	0	USA	PC	B, W	49%		51%	CC	GA
Kramer et al. [38]	2009	0	Canada	PC	B, W, H	80%	5%	8%	OR	SPTB
Lobel et al. [41]	2000	0	USA	PC	W	87%			CC	GA
Mancuso et al. [42]	2004	0	USA	PC	B, W, H	24%	32%	43%	CC	GA
McDonald et al. [43]	2014	0	Canada	PC	W	80%			OR	PTB
Orr et al. [44]	2007	0	USA	PC	B, W	23%		77%	OR	SPTB
Peacock et al. [46]	1995	0	England	PC	W	100%			OR	SPTB
Perkin et al. [20]	1993	2	England	PC	W	100%			OR	PTB
Rini et al. [48]	1999	0	USA	PC	W, H	48%	52%		CC	GA
Roesch et al. [14]	2004	1	USA	PC	B, W, H	23%	35%	43%		PTB: GA
Uguz et al. [15]	2013	1	Turkey	CS	Turkey					GA
Wadhwa et al. [50]	1993	0	USA	PC	B, W, H	77%	13%	7%	OR, CC	PTB: GA
Bhagwanani et al. [16]	1997	1	USA	PC	B, W, H	65%	8%	27%		PTB
Andersson et al. [24]	2004	0	Sweden	PC	Sweden				OR	PTB: SPTB
Bindt et al. [26]	2013	0	G/C D’I	PC	G/C D’I				OR, CC	PTB: GA
Bödecs et al. [17]	2011	1	Hungary	PC	Hungary					PTB
Catov et al. [27]	2010	0	USA	PC	B, W	70%		30.0%	OR	PTB
Dayan et al. [30]	2006	2	France	PC	W	94%			OR	PSTB
Dominguez et al. [32]	2008	0	USA	PC	B, W	100%		100%	CC	GA
Latendresse and Ruiz [39]	2011	0	USA	PC	B, W, H	69%	23%	4%		PTB
Lobel et al. [40]	2008	0	USA	PC	B, W, H	65%	12%	12%	OR	SPTB: GA
Amiri et al. [23]	2010	2	Iran	PC	Iran				OR	PTB
Rauchfuss and Maier [21]	2011	2	Germany	PC	Germany				OR	PTB
Sanchez et al. [49]	2013	0	Peru	CC	Peru				OR	SPTB
Martini et al. [22]	2010	2		PC	Germany				OR	PTB
Powell et al. [47]	2013	2	Australia	RCT	Australia				OR	PTB
Ibanez et al. [37]	2012	0	France	PC	France				OR	PTB: SPTB
Levi et al. [18]	1989	1	Sweden	PC	Sweden					PTB: GA
Pagel et al. [45]	1990	0	USA	PC	B, W	78%		7%	C	GA

Ghana/Cote D’Ivoire.

(b)

Author	Year	PPV	Scale	# Items	Item score; score	Range	Cut-off	# Obs	Times	MMM	Trimester
Berle et al. [25]	2005	Anxiety	HADS-A	7	1_4	0–21	≥8	1	Anytime
Copper et al. [29]	1996	Trait	STAI	5	1_5	20	C	1	26 ± 0.8 w		L2/E3
Dole et al. [31]	2004	PSA	PSIS	6	0_3	18		1	24–29 w		L2/E3
Dominguez et al. [33]	2005	State, PSA	STAI, RD	10	1_4	10–40	ns	3	18–20 w, 24–26 w, 32–36 w	Mean	2/3
Field et al. [34]	2010	Anxiety	SCID	20		20–90	48	1	20 w		2
Glynn et al. [35]	2008	PSA	Rini	10	1_4	10–40		2	19.3 w, 31.0 w	Both	2/E3
Goldenberg et al. [19]	1996	Trait	STAI	ns	ns	ns	ns	1	24–26 w		L2
Hosseini et al. [36]	2009	Trait	STPI	10	1_4	10–40	NA	2	4 m, 7 m	First	2
Kramer et al. [38]	2009	PSA	D-S	4	1_5	16	Q	1	24–26 w		L2
Lobel et al. [41]	2000	State	STAI	20	1_4	60		3	10–20 w, 21–30 w, >31 w	3 CC	1/E3
Mancuso et al. [42]	2004	PSA: State	RD; STAI	4	1_5	16	NA	3	18–20 w, 28–30 w	2 CC	2/E3
McDonald et al. [43]	2014	State	STAI	20	1_5		40	1	<25 w		L2
Orr et al. [44]	2007	PSA	PSEI	6	0_1	0–6	≥4	1	1st prenatal visit		1
Peacock et al. [46]	1995	Anxiety	GHQ			0–21	Q	1	b		1
Perkin et al. [20]	1993	Anxiety	GHQ				Q	3	b, 28 w	Max	1/E3
Rini et al. [48]	1999	PSA	Wadhwa	10	1_4	30		1	28–32 w		E3
Roesch et al. [14]	2004	State	STAI	10	1_4	30		3	18 w, 28 w		L/E3
Uguz et al. [15]	2013	PSA	PSA	4	1_5	16		1	36 w GA - 8 w PP	First	3
Wadhwa et al. [50]	1993	PSA	PAIP	5	0_1	0–5	C	1	28–30 w		L2/E3
Bhagwanani et al. [16]	1997	PSA	RD	5	1_5	20		5	8–28 w, then + 6 w		1/E3
Andersson et al. [24]	2004	AD	PRIME-MD				B	1	16–18 w		2
Bindt et al. [26]	2013	AD	GAD-7	7	0_3	0–21	≥10	1	3 trimester		3
Bödecs et al. [17]	2011	AD	GAD-7					1	M = 8.13		1
Catov et al. [27]	2010	Trait	STAI-T	10	1_4	10–40	>20	1	M = 17.9		L2/E3
Dayan et al. [30]	2006	State: Trait	STAI-Y	40	1_4	20–80	C	1	20–28 w		2
Dominguez et al. [32]	2008	State: Trait	STAI-Y	40	1_4	60		3	18–20 w, 24–26 w, 30–32 w	Mean	2/E3
Latendresse and Ruiz [39]	2011	PSA	RD		1_5			1	14–20		2
Lobel et al. [40]	2008	State	STAI					3	10–25 w, 21–30 w, >30 w	3 CC	L1/2
Amiri et al. [23]	2010	State	STPI	10	1_4	30		1	20–28 w		L2/E3
Rauchfuss and Maier [21]	2011	Anxiety: PSA	RD; Lukesch	5,3		0–5; 0–6		1	13–24 w		2
Sanchez et al. [49]	2013	Anxiety	DASS-21	4			≥10	1	PP		PP
Martini et al. [22]	2010	AD	DSM-IV				B	1	PP		PP
Powell et al. [47]	2013	State: Trait	STAI-6				C	1	Mean 19.7		L2/E3
Ibanez et al. [37]	2012	State	STAI	20	1_4	20–80	≥37	1	24–28 w		L2/E3
Levi et al. [18]	1989	S, P, C	CAI	7	?	?	?	1	36 w		3
Pagel et al. [45]	1990	State	STAI	20	1_4	20–80		1	21-36 w		L2/E3

(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		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