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• Re:Is the effect of parental separation underestimated?
  Maria Quigley
  Published on: 20 December 2013
• Is the effect of parental separation underestimated?
  Michael A. Colvin
  Published on: 6 December 2013

• Published on: 20 December 2013

  Re:Is the effect of parental separation underestimated?

  • Maria Quigley
  • Other Contributors:
    • Claire Carson, Julia Morinis

  Maria A Quigley1, Claire Carson1, Julia Morinis1,2,3.

  1 National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK

  2 Department of Paediatric Medicine, Hospital for Sick Children, Toronto, Ontario, Canada

  3 Centre for Research on Inner City Health, The Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada

  We would like to...

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  Maria A Quigley1, Claire Carson1, Julia Morinis1,2,3.

  1 National Perinatal Epidemiology Unit, University of Oxford, Oxford, UK

  2 Department of Paediatric Medicine, Hospital for Sick Children, Toronto, Ontario, Canada

  3 Centre for Research on Inner City Health, The Keenan Research Centre, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada

  We would like to thank Michael A Colvin for highlighting the distinction between the presence of the child's biological father in the household and the presence of the mother's partner in the household. As Dr Colvin points out, the data in Table 1 of our paper suggest that 14% of five year old children in the study do not have their father living in their home and, among the children of teenage mothers, this proportion is 53.5%. We thank Dr Colvin for highlighting this as this variable is labelled incorrectly in Table 1 of our paper and it should read as 'Partner in the home at 5 years' (i.e. this would not necessarily be the child's father) rather than 'Father in the home at 5 years'. We have also looked at the effects on child cognitive ability of having the biological father resident in the family home, both at the first survey (9 months) and at the five-year follow-up. Overall, 73% of children had their father resident at both surveys and 12.5% had their father leave by the time of the five year survey; in the families with teenage mothers, these proportions were 21.4% and 24.8% respectively. In addition, compared with children whose fathers were in the home at both surveys, there was a statistically significantly lower BAS Naming Vocabulary score in children whose fathers had left during the study (-3.8), or who were not living in the home at either survey (-7.2). In the small number of children whose fathers were not there at baseline, but had returned to the family home during the study, there was also an adverse effect on BAS Naming Vocabulary score (-4.9), hence suggesting a negative impact of family instability, as has been found in other studies, including the Millennium Cohort Study. However, after adjusting for the other variables in our models, the effect of family instability was not statistically significant and did not alter our coefficients for mother's age (data available on request). For example, model E from Table 2 of our paper shows a statistically significantly lower BAS Naming Vocabulary score in children of teenage mothers compared with children of mothers aged 25-34 (-3.8, 95% CI: -6.3 to -1.3). When we replaced 'marital status' (which does not distinguish between father and partner, or change of partner) in this model with 'family instability' (as measured by the natural father's residence in the child's home at both surveys) the effect of teenage motherhood was very similar (-3.9, 95% CI -6.4 to -1.5). Hence, we believe that the conclusions drawn from our study are robust.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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• Published on: 6 December 2013

  Is the effect of parental separation underestimated?

  • Michael A. Colvin, Consultant Paediatrician

  Morinis et al conclude that there remains a significant adverse effect on verbal abilities in children born to teenage mothers at age five years of age after adjustment for sociodemographic circumstances and perinatal risk. However there appears to be a flaw in the methodology of the study which undermines its findings. In the characteristics of the study population by age group (table 1), the response "Father at home- No...

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  Morinis et al conclude that there remains a significant adverse effect on verbal abilities in children born to teenage mothers at age five years of age after adjustment for sociodemographic circumstances and perinatal risk. However there appears to be a flaw in the methodology of the study which undermines its findings. In the characteristics of the study population by age group (table 1), the response "Father at home- No" rises from 51.7% at 9 months to 53.5% at 5 years. Implausibly, reading across the data for all age groups, the parental relationships involving teenage mothers would appear more stable over this period than those in any other age group. The presence of the father at home falls for the other age groups by between 3 and 6%. Clinical experience indicates that a substantial proportion of the young mothers will have separated from the child's father and have begun a new relationship in the 4 year interval. It would appear that the study equates the presence of any male partner with having the child's father in the home. The Institute of Fiscal Studies, also using a sample of the Millennium Cohort Study, found that 20% and 27% of unmarried cohabiting parents had separated by the time the child was three and five years old respectively. This is of no small consequence for the Morinis study because the IFS also found that the separation of the birth parents was the most significant adverse influence on the cognitive outcomes for children. If, as it appears, any male partner has been considered as the father, and the effect of the separation of a child's natural parents has not been taken into account, the conclusions by Morinis are unsafe.

  Goodman, A. and Greaves, E. (2010) Cohabitation, Marriage and Child Outcomes, IFS Commentary C114, Institute of Fiscal Studies.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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