Table 2.
Studies included within the analysis
| Reference/country | Number of infants | Infant age | Assessment | Subcategory | Effect size (Cohen's d) | Covariates controlled for in the analysis | Overall bias |
|---|---|---|---|---|---|---|---|
|
Barros et al10 Brazil |
388 infants (365 not exposed, 23 exposed) | 24‐72 h old | NICU Network Neurobehavioural Scale | Attention | −1.3 | Anaesthesia at birth, type of delivery, gender, age of newborn at assessment, time since last feed and duration of assessment | Low |
| Excitability | −0.636 | ||||||
| Lethargy | −1.142 | ||||||
| Stress | −0.587 | ||||||
|
Espy et al56 USA |
304 infants (161 not exposed, 143 exposed) | 2 d old | Neonatal Temperament Assessment | Attention | −0.465 | Mothers' IQ estimate. Marital status, maternal age, education, income, alcohol intake, newborn gender, race, SHS exposure, medication use, gravida, parity, weight gain, maternal health, delivery health, BSI summary index, CAARS:S Attention Deficit/Hyperactivity Disorder index and BIA IQ estimate | Low |
| Irritability | −0.192 | ||||||
|
Godding et al57 Belgium |
33 infants (16 not exposed, 17 exposed) | Up to 5 d old | Neurological Scores and Finnegan Withdrawal Scores | Muscle tone | −0.3785 | Term of pregnancy and feeding method | Low |
|
Hernandez‐Martinez et al34 Spain |
265 infants (203 not exposed, 62 exposed) | 48‐72 h old | Neonatal Behavioural Assessment Scale | Negative affect | −0.02 | Socio‐economic status, birthweight and gestational age. Maternal age, socio‐economic status, newborn gender, birthweight, gestational age, Apgar scores, parity, delivery type, trait anxiety | Low |
| Excitability | −0.44 | ||||||
| Orientation | −0.35 | ||||||
| Regulation | −0.351 | ||||||
|
King et al58 USA |
48 infants (24 not exposed, 24 exposed) | 3‐5 mo | Response to bell ring, brain response | Orientation | −0.8471 | Maternal education, gestation at birth, age at assessment, birthweight, ethnicity | Moderate |
|
Law et al32 USA |
56 infants (29 not exposed, 27 exposed) |
Between 36 and 41 wk gestational age | NICU Network Neurobehavioural Scale | Excitability | −0.829 | Parity, 5‐min Apgar scores and birthweight. Maternal age, gravida, education, employment, socio‐economic status, alcohol use, gestational age, Apgar score at 1 min | Low |
| Muscle tone | −0.711 | ||||||
| Stress | −1.510 | ||||||
|
Mansi et al31 Italy |
50 infants (25 not exposed, 25 exposed) | 56‐72 h old | Neonatal Behavioural Assessment Scale | Attention | −1.358 | Gender, gestational age, postnatal age, birthweight, Apgar scores, bilirubin | Low |
| Irritability | −1.949 | ||||||
| Muscle tone | −1.010 | ||||||
| Orientation | −1.115 | ||||||
| Regulation | −0.599 | ||||||
|
Mundy39 UK |
71 infants (47 not exposed, 24 exposed) | 6 mo | Laboratory Temperament Assessment Battery and Infant Behaviour Questionnaire | Difficult temperament | −0.556 | None noted | Moderate |
|
Mundy39 UK |
71 infants (47 not exposed, 24 exposed) | 6 mo | Laboratory Temperament Assessment Battery and Infant Behaviour Questionnaire | Negative affect | −0.409 | None noted | |
| Difficult temperament | −0.399 | ||||||
|
Pickett et al37 UK |
15 943 infants (11 747 not exposed, 4196 exposed) | 9 mo | Carey Infant Temperament Scale | Negative affect | −0.759 | None noted | Moderate |
| Orientation | −0.070 | ||||||
| Regulation | −0.114 | ||||||
| Difficult temperament | −0.134 | ||||||
|
Saxton38 UK |
32 infants (17 not exposed, 15 exposed) | 4‐6 d old | Neonatal Behavioural Assessment Scale | Orientation | −0.8471 | None noted | Moderate |
| Regulation | −0.782 | ||||||
|
Schuetze et al29 USA |
115 infants (46 not exposed, 69 exposed) | 2‐4 wk old and again at 7 mo old | Infant Behaviour Questionnaire | Negative affect | −0.806 | Mothers' age, education, socio‐economic status, parity, number of prenatal visits, substance use, infant birthweight, head circumference and birth length | Low |
|
Shisler et al30 USA |
258 infants (77 not exposed, 181 exposed) | 2 and 9 mo old | Focused attention assessment and behavioural reactivity | Attention | −0.238 | Mothers' age, education, prenatal alcohol and marijuana, partner status, birthweight, gestational age, gender, head circumference at birth | Low |
|
Stroud et al35 USA |
56 infants (28 not exposed, 28 exposed) | 17 d old | NICU Network Neurobehavioural Scale | Excitability | −0.665 | Maternal SHS exposure, infant SHS exposure, feeding, maternal depression, socio‐economic status, maternal age and depression | Low |
| Regulation | −0.565 | ||||||
|
Stroud et al48 USA |
962 infants (366 not exposed, 596 exposed) | <3 d old | Graham‐Rosenblith Behavioural Examination | Irritability | −0.125 | Maternal age, race, socio‐economic status, birthweight and infant age at assessment. Gravida, parity, Apgar score at 1 min and Apgar score at 5 min | Low |
| Muscle tone | −0.308 | ||||||
|
Wiebe et al59 USA |
218 infants (91 not exposed, 127 exposed) | 6 mo old | A battery of assessments including attention, regulation and inhibition | Orientation | −0.236 | Propensity scores—alcohol in first month of pregnancy, maternal age, education, IQ, hyperactivity. Parental stress and infant exposure | Moderate |
|
Yolton et al22 USA |
251 infants (218 not exposed, 33 exposed) | 5 wk old | NICU Network Neurobehavioural Scale | Attention | −0.134 | Birthweight, age at assessment and infant gender. Maternal age, income, employment, education, marital status, parity, marijuana and alcohol use, maternal blood lead in pregnancy and weight change since birth and maternal depression | Low |
| Lethargy | −0.147 | ||||||
| Regulation | −0.067 | ||||||
| Stress | −0.002 |