Nav: Home

A mother's age doesn't matter

June 01, 2017

A number of previous scientific studies have found that among mothers 35 or older, there is an elevated risk that their children are born preterm (less than 37 weeks of pregnancy) or with low birth weight (less than 2.5 kilograms).

Low birth weight children have more respiratory, cognitive, and neurological problems than those born with normal weight. Preterm babies have elevated risks of heart defects, lung disorders, brain damage, and delayed development. The mean age of women at childbearing has been rising for the last decades in high income countries making these risks highly relevant.

However, advanced maternal age per se does not seem to be causing the increase in birth risks. This is the finding of a new study that has just been published in the American Journal of Epidemiology which was conducted by Mikko Myrskylä, director of the Max Planck Institute for Demographic Research (MPIDR) and Alice Goisis from the London School of Economics.

The researchers looked at thousands of Finnish families where at least two children were born to the same mother between 1987 and 2000. They found that within the same family the advancing age of the mother did not increase the risk of poor birth outcomes.

In contrast, when they compared children born to different mothers at different ages, risks went up notably with the age of the mother. For example, the probability of a low weight birth for a mother age 40 and above is twice as high (4.4 percent) as compared to a woman between 25 and 29 (2.2 percent).

Thus, on the whole, preterm deliveries or low birth weights still occur more often when the mother is older. "A doctor who only knows the age of a pregnant woman can still use her age to predict the birth risk," says Mikko Myrskylä.

"However, for the individual mother, age is not the real cause of the increase in birth risks," explains Alice Goisis. "The true reasons are more likely to be individual circumstances in the life of the parents or behaviors that are more common in older adults."

The new study did not focus on these true reasons. Searching for them would require a different method and even more detailed data than is available from the Finnish registers that the scientists used for this study.

Potential candidates for these individual risk factors could be fertility problems, which are associated both with the risk of poor birth outcomes and with an older maternal age at birth, the level of maternal stress, and unhealthy behaviors, say the authors.

By looking at children born to the same mother, the researchers could isolate the effect of pure age on the risk of poor birth outcomes. Most other potentially influencing factors could be excluded by this type of analysis, because while they vary between different families, they don't vary between pregnancies of any individual woman.

Factors that do change from one birth to the next for the same mother - such as family income and birth order - could be excluded as reasons for elevated risks by controlling for them statistically.

In effect, when only the age of the mother changed in the statistical calculations, the increase in birth risks disappeared.

"Our findings suggest that women should not be concerned about their age per se, when considering to have a child," says demographer Myrskylä. "It seems that individual life circumstances and behavioral choices are more important than age."
Original paper:

Alice Goisis, Hanna Remes, Kieron Barclay, Pekka Martikainen, Mikko Myrskylä: Advanced maternal age is not an independent risk factor for low birth weight or preterm birth, American Journal of Epidemiology, DOI 10.1093/aje/kwx177

(online version initially as unedited manuscript, accepted by the journal)


Related Low Birth Weight Articles:

Internet-based weight-loss program for low-income women after child birth
An internet-based weight loss program was effective in promoting significant weight loss in low-income postpartum women over 12 months, according to a study published by JAMA.
Study shows link between maternal marijuana use and low birth weight
Researchers at Lawson Health Research Institute, Western University and Brescia University College found that women who used marijuana while pregnant were almost three times more likely to have an infant with low birth weight.
Link found between financial strain and low-birth-weight babies
A financially strapped pregnant woman's worries about the arrival and care of her little one could contribute to birth of a smaller, medically vulnerable infant, a new study suggests.
Both low and high birth weight linked to fatty liver disease in children
Both high and low birth weights show increased risk for developing nonalcoholic fatty liver disease.
Living downwind of coal-fired power plant could increase risk of low birth weight
Drawing on evidence from a Pennsylvania power plant located upwind of New Jersey, a group of researchers led by Muzhe Yang of Lehigh University studied live singleton births that occurred from 1990 to 2006 in the area downwind of the plant.
Low birth weight babies at higher risk for mental health problems later in life
Babies born with extremely low birth weight are not only at risk for physical problems but are also more likely to experience mental health problems later in life, according to an analysis of research conducted over nearly 30 years.
Study: Depression in pregnancy, low birth weight tied to biomarker
A biomarker in pregnant women is linked to depression and low fetal birth weight.
Maternal gastric bypass may be associated with low birth weight babies
Women who undergo gastric bypass surgery for weight loss risk giving birth to babies that are small or have lower average birth weights.
Babies born with a low birth weight may be less active in later life
Individuals who are born with a low birth weight are less likely to be good at sports at school or participate in exercise later on in life.
Steroid treatment in very low birth weight infants may contribute to vision problems
It has long been suspected that steroids may have negative neurodevelopmental effects on very premature infants.

Related Low Birth Weight Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...