Table 4.
Characteristics of studies that were not included in the meta-analysis
| Author, year | Study design | Confounders | Outcome | Result |
|---|---|---|---|---|
| Antoniades 2003 [17] | Cohort study | Height, age |
Bone Mineral density (BMD) and bone mineral content (BMC) at the lumbar spine, Hip and forearm |
No association was found with LBW |
| Bergvall 2007 [31] | Cohort study | Zygosity and socioeconomic factors, genetic factors, shared familial environment, BMI | Hypertension | Decreased birth weight was found to be associated with increased risk of hypertension |
| Cnattingius 2009 [19] | Cohort study | Mother’s short status | Late fetal death rates | The risk of late fetal death is greatly increased in twin fetuses |
| De Zeeuw 2012 [20] | Cohort study | Mode of delivery, gestational age and zygosity | Educational achievement in primary school | Low birth weight were the most important risk factors for lower educational achievement of twins in primary school |
| Groen-Blokhuis 2011 [21] | Cohort study | Zygosity | Attention problems | Association of birth weight and attention problems represented a causal relationship |
| Hestbaek 2003 [22] | Cohort study | Birth factors and anthropometric measures in adolescence | Low back pain | The odds ratio for the lifetime prevalence of low back pain increases from 1.21 (0.94-1.56) for a birth weight of 2000-2500 g to 1.97 (1.35-2.88) for a birth weight of > 3500 g compared to the smallest weight group (< 2000 g) in males, whereas there is a small statistically insignificant, positive association for females. |
| Hultman 2007 [23] | Cohort study | Fetal growth restriction | Attention-deficit/hyperactivity disorder in childhood and early adolescence | Low birth weight was a risk factor for symptoms of attention-deficit/hyperactivity disorder and the associations did not diminish when we controlled for genetic influence |
| Williams 1996 [24] | Cohort study | Gestational age | Cerebral palsy | The relative risk was greatest in twins weighing more than 2499 g (4.5). However, after adjusting for reduced birthweight of twins it was the relative risk of twins weighing less than 1400 g that was significantly increased. |
| Yokoyama 2007 [29] | Cohort study | Gestational age | Motor development in early life | The mean age at achieving milestones was slower in twins with normal birth weight than singletons |