Causal Hypothesis for Some Congenital Anomalies

Pharoah, P. O. D.

doi:10.1375/183242705774860141

Cited by 16 publications

(10 citation statements)

References 38 publications

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“…However, multiple delivery did not pose a risk to birth defect in Europe [28]. Alterations of the blood flow within the vascular anastomoses supplying the twins and early primary abnormality that might develop during twinning itself can lead to birth defects [29].…”

Section: Discussionmentioning

confidence: 99%

Burden and consequence of birth defects in Nepal-evidence from prospective cohort study

et al. 2021

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Background Every year an estimated 7.9 million babies are born with birth defect. Of these babies, more than 3 million die and 3.2 million have disability. Improving nationwide information on prevalence of birth defect, risk factor and consequence is required for better resource allocation for prevention, management and rehabilitation. In this study, we assess the prevalence of birth defect, associated risk factors and consequences in Nepal. Method This is a prospective cohort study conducted in 12 hospitals of Nepal for 18 months. All the women who delivered in the hospitals during the study period was enrolled. Independent researchers collected data on the social and demographic information using semi-structured questionnaire at the time of discharge and clinical events and birth outcome information from the clinical case note. Data were analyzed on the prevalence and type of birth defect. Logistic regression was done to assess the risk factor and consequences for birth defect. Results Among the total 87,242 livebirths, the prevalence of birth defects was found to be 5.8 per 1000 live births. The commonly occurring birth defects were anencephaly (3.95%), cleft lip (2.77%), cleft lip and palate (6.13%), clubfeet (3.95%), eye abnormalities (3.95%) and meningomyelocele (3.36%). The odds of birth defect was higher among mothers with age < 20 years (adjusted Odds ratio (aOR) 1.64; 95% CI, 1.18–2.28) and disadvantaged ethnicity (aOR 1.78; 95% CI, 1.46–2.18). The odds of birth asphyxia was twice fold higher among babies with birth defect (aOR 1.88; 95% CI, 1.41–2.51) in reference with babies without birth defect. The odds of neonatal infection was twice fold higher among babies with birth defect (aOR 1.82; 95% CI, 1.12–2.96) in reference with babies without birth defect. Babies with birth defect had three-fold risk of pre-discharge mortality (aOR 3.00; 95% CI, 1.93–4.69). Conclusion Maternal age younger than 20 years and advantaged ethnicity were risk factors of birth defects. Babies with birth defect have high risk for birth asphyxia, neonatal infection and pre-discharge mortality at birth. Further evaluation on the care provided to babies who have birth defect is warranted. Funding Swedish Research Council (VR).

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Section: Discussionmentioning

confidence: 99%

Burden and consequence of birth defects in Nepal-evidence from prospective cohort study

et al. 2021

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“…Others hypothesise that placental vascular anastomoses between the monozygotic co-twins’ circulations may lead to fluctuations in blood flow during fetal heart development, causing CHD. 25 26 If the aetiology of CHD in twins is predominantly haemodynamic as opposed to genetic, this may explain why chromosomal anomalies were less common in twins with CHD compared with singletons. Alternatively, monozygotic twinning itself is hypothesised to be part of a morphogenic anomaly which leads to a congenital anomaly.…”

Section: Discussionmentioning

confidence: 99%

Increased risk of congenital heart disease in twins in the North of England between 1998 and 2010

Best

Rankin

2015

Heart

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ObjectiveTo examine the relative risk (RR) of congenital heart disease (CHD) in twins compared with singletons, according to chorionicity.MethodsTwins and singletons with CHD notified to the Northern Congenital Abnormality Survey between 1998 and 2010 were included in this population-based study. Information on chorionicity was obtained from the Northern Survey of Twins and Multiple Pregnancy. Prevalence was calculated as the number of cases occurring in live births, late miscarriages (20–23 weeks), stillbirths (≥24 weeks) and terminations of pregnancy for fetal anomaly, per 10 000 total births. The risk of CHD in twins compared with singletons was estimated using Poisson regression.ResultsThere were 399 414 singleton births of which 2984 (0.7%) had CHD. Among 11 871 twin births, 154 (1.3%) had CHD; one twin was affected by CHD in 2.5% of twin pregnancies. Of 8605 dichorionic (DC) births and 2317 monochorionic (MC) births, 96 (1.1%) and 47 (2.0%) were associated with CHD. Compared with singletons, twins were at significantly increased risk of CHD (RR=1.73, 95% CI 1.48 to 2.04; p<0.001). MC twins were at 82% significantly increased risk of CHD compared with DC twins (RR=1.82, 95% CI 1.29 to 2.57; p<0.001). The RR of severe and mild CHD was particularly high in MC twins compared with singletons (292% increased risk, RR=3.92, 95% CI 1.25 to 12.30, p=0.02 and 207% increased risk, RR=3.07, 95% CI 2.20 to 4.28; p<0.001).ConclusionsCompared with singletons, twins were at increased risk of CHD, the risk being substantially higher among MC twins. This information is important for health professionals when counselling women with twin pregnancies.

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“…However, the significant difference between same-and opposite-sex twins when neonatal and postneonatal mortality are separately examined, suggests that the role of zygosity in some subsets of twin SIDS should be reassessed. Monozygous twins are always same-sex and are at significantly increased risk of infant mortality and severe morbidity, particularly neurological impairment, in those who survive (Pharoah, 2005). The neurological abnormalities include holoprosencephaly, schizencephaly, hydranencephaly, porencephaly and multicystic encephalomalacia (Scheller & Nelson, 1992).…”

Section: Sudden Infant Death Syndrome In Twins and Singletonsmentioning

confidence: 99%

Sudden Infant Death Syndrome in Twins and Singletons

Pharoah¹,

Platt

2007

Twin Res Hum Genet

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T wins compared with singletons and monozygous (MZ) compared with dizygous (DZ) twins are at increased risk of fetal and infant death, cerebral palsy and many congenital anomalies. The aim of this study is to investigate whether zygosity is a risk factor for the sudden infant death syndrome (SIDS). Birth registration data and draft infant death certificates for all multiple births in England and Wales 1993 to 2003 were provided by the Office for National Statistics. As a partial proxy for zygosity, same-sex was compared with opposite-sex twins for birthweight-specific mortality and mortality attributed to SIDS. Data on singleton infants were obtained by subtraction of multiple births from routinely published population births and infant deaths. SIDS mortality among low birthweight infants was significantly less in twins than singletons. The twin-singleton relative risk was reversed in infants of normal birthweight. Among infants of normal birthweight, neonatal SIDS was significantly more common in same-compared with opposite-sex pairs. Among infants of low birthweight, postneonatal SIDS was significantly more common in same-compared with opposite-sex pairs. The difference in birthweight distribution of same-compared with opposite-sex twins for neonatal SIDS suggests that zygosity is a risk factor for SIDS. As congenital cerebral anomalies are a feature of many monozygous twin conceptions, a detailed macro-and microscopical examination of the brain in twin SIDS may indicate an otherwise unrecognised pathology.The association of increased risk of Sudden Infant Death Syndrome (SIDS) with environmental factors such as sleeping position and over-heating from swaddling is well known. Public education about these risks has contributed to a decreasing trend in the incidence of SIDS. Pre-term or low birthweight has an independent effect from sleeping position on the risk of SIDS (Blair et al., 2006;Thompson et al., 2006). The crude relative risk is also greater in twins compared with singletons and adjustment should be made for the confounding effect of low birthweight (Malloy & Freeman, 1999).We previously reported on the epidemiology of SIDS in twins and singletons in England and Wales 1993 to 1998, confirmed that twins compared with singletons were at significantly increased risk and observed that in both twins and singletons the risk of SIDS increased with decreasing birthweight. The higher crude relative risk in twins was attributable to the higher proportion of twins that were of low birthweight. The hypothesis that some SIDS deaths in twins may have been attributable to unrecognized prenatally acquired cerebral impairment associated with monozygotic monochorionic twinning was tested using, as a partial proxy for zygosity, a comparison of same-and opposite-sex twin SIDS mortality. No significant difference was found and it was concluded that zygosity was not an important factor (Platt & Pharoah, 2003).The study now reported complements the earlier one by extending the analysis to cover the years 1993 to 2003. The a...

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Causal Hypothesis for Some Congenital Anomalies

Cited by 16 publications

References 38 publications

Burden and consequence of birth defects in Nepal-evidence from prospective cohort study

Burden and consequence of birth defects in Nepal-evidence from prospective cohort study

Increased risk of congenital heart disease in twins in the North of England between 1998 and 2010

Sudden Infant Death Syndrome in Twins and Singletons

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