Study finds both cousin marriage and older mothers double risk of birth defects

July 3, 2013
Important research has shed light on the prevalence of congenital anomalies. Credit: US National Institutes of Health

Marriage between first cousins can more than double the risk of giving birth to a baby with a congenital anomaly (eg, heart and lung defects, Down syndrome), although the absolute risk is low, according to a multiethnic study of more than 11300 babies from the city of Bradford in the UK, published in The Lancet.

The high level of consanguineous marriage (marriage between blood relatives) within the large Pakistani community in the study* accounted for nearly a third (31%) of in babies of Pakistani origin.

A similar but expected increased risk in (over 34 years of age) was seen among white British women.

"It is important to note that the absolute increase in risk is small (from 3% to 6%), meaning that only a of babies born to couples who are blood relatives or older mothers (older White British mums have an increase in risk from 2% to 4%) will develop a congenital anomaly"**, cautions lead author Eamonn Sheridan from the University of Leeds in the UK.

The investigators looked at the influence of various maternal lifestyle and clinical risk factors (eg, smoking, obesity, and deprivation) in children with one or more anomalies from the Born in Bradford (BiB) study, which is tracking the health of 13 500 babies born at Bradford Royal Infirmary between 2007 and 2011, but found that the greatest risk factor was closely-related parents.

Overall rates of congenital anomalies in the BiB babies (305.74 per 10000 livebirths) were almost double national rates (165.90 per 10000 livebirths).

Socioeconomic status did not explain the increased rates of birth defects in offspring of blood relatives, despite two-thirds of the babies in the study coming from the most deprived fifth of the UK population.

What is more, in contrast with previous research, maternal smoking, , and obesity were not identified as for birth defects in this cohort, although the study may not have been large enough to detect the increases in risk associated with these factors.

A high level of maternal education was protective irrespective of ethnic origin, roughly halving the risk of having a baby with a congenital anomaly.

Consanguinity is a deeply rooted social trend with more than one billion people worldwide currently living in communities where consanguineous marriages are commonplace.

According to Neil Small from the University of Bradford who co-led the research, "This is the first study that has been able to explore all causes of in a population where there are sufficient numbers in both consanguineous and non-consanguineous groups to come to reliable conclusions. Clear and accessible information on these small but significant avoidable risks should be widely disseminated to local communities and be included as part of antenatal counselling and in the planning of healthcare services." **

Commenting on the study, Alan Bittles from Murdoch University and Edith Cowan University in Perth, Australia writes, "Sheridan and colleagues deserve major credit for their complex, time-consuming, and socially sensitive study… In view of the high community support for the Born in Bradford programme, a complementary substudy to determine the effects of consanguinity and community endogamy [when individuals marry within the same ethnic, class, or social group] on adult-onset diseases would be an invaluable investment for the future."

Explore further: The number of multiple births affected by congenital anomalies has doubled since the 1980s

More information: www.thelancet.com/journals/lan … (13)61132-0/abstract

Related Stories

The number of multiple births affected by congenital anomalies has doubled since the 1980s

February 5, 2013
The number of congenital anomalies, or birth defects arising from multiple births has almost doubled since the 1980s, suggests a new study published today (6 February) in BJOG: An International Journal of Obstetrics and Gynaecology.

Younger mothers and older mothers are at higher risk of adverse delivery outcomes

June 11, 2013
Younger mothers are at a higher risk of preterm birth while older mothers are more likely to have a caesarean section, suggests a new study published today (12 June) in BJOG: An International Journal of Obstetrics and Gynaecology.

Overweight mothers who smoke while pregnant can damage baby's heart

January 30, 2012
Mums-to-be who are both overweight and smoke during their pregnancy risk damaging their baby's developing heart, finds research published online in Heart.

Poor maternal and child health linked with premature high blood pressure, kidney disease

June 19, 2013
(Medical Xpress)—How babies grow and develop in the womb, as newborns and into childhood can put them at increased risk for premature high blood pressure, kidney disease and heart disease, according to a research review ...

Study reveals mothers' migrant status linked to newborns' weight

June 27, 2013
A new study involving Oxford University researchers suggests that the migrant status of couples in Hong Kong is a key factor in their babies' birth weights.

Rubella in pregnancy rare in US, but can be devastating for baby

March 28, 2013
(HealthDay)—Although rare in the United States, three babies with birth defects caused by rubella (or "German measles") were reported in 2012 and doctors need to be on the lookout for such cases, a new government report ...

Recommended for you

Women exposed to smoke while in womb more likely to miscarry

July 13, 2017
Women exposed to cigarette smoke while in their mothers' wombs are more likely to experience miscarriage as adults, according to new research from the University of Aberdeen.

Lack of a hormone in pregnant mice linked to preeclampsia

June 30, 2017
(Medical Xpress)—A team of researchers from Singapore, the Netherlands and Turkey has isolated a hormone in pregnant mice that appears to be associated with preeclampsia—a pregnancy-related condition characterized by ...

Aspirin reduces risk of pre-eclampsia in pregnant women

June 28, 2017
Taking a low-dose aspirin before bed can reduce the risk of pre-eclampsia, which can cause premature birth and, in extreme cases, maternal and foetal death.

The biology of uterine fluid: How it informs the fetus of mom's world

June 22, 2017
A developing fetus bathes in a mixture of cellular secretions and proteins unique to its mother's uterus. Before fertilization, the pH of uterine fluid helps create a conducive environment for sperm migration, and afterward, ...

New clues in puzzle over pre-eclampsia and cholesterol regulation

June 21, 2017
Scientists studying a mystery link between the dangerous pregnancy complication pre-eclampsia and an increased risk of heart disease in later life for both mother and child have uncovered important new clues.

Are maternal hormones different when carrying a boy or a girl?

June 15, 2017
With advances in prenatal testing it's now possible to find out whether a pregnancy will result in a male or female baby as early as eight weeks' gestation.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.