Summer vs Winter Babies – Does the Season of Birth Determine Your Child’s Behaviour?

Forget about charting your child’s star sign, new studies have found that summer and winter babies exhibit different behavioural characteristics.

To determine how birth season affects a child’s characteristics, Queensland University of Technology (QUT) researchers matched the birth months of nearly 5000 children aged four and five with their results from a behavioural screening questionnaire.

They found children born in summer months (November to January) exhibited poorer behaviour than children born in winter months (May to July).

The questionnaire assessed behaviours such as consideration of others, sharing, temperament, fidgeting, concentration and ability to make friends.

QUT associate professor of health Adrian Barnett suspects children’s behavioural characteristics are linked to their exposure to vitamin D via sunlight while in utero.

“Those born in summer tend to do worse [behaviourally]. This could be because they missed the peak vitamin D time,” Mr Barnett said.

“Pregnancies with summer right in the middle will likely get the highest vitamin D levels.”

Birth season has previously been proved to be an environmental factor that affects a child’s physical, social and psychological characteristics.

Researchers believe the level of vitamin D at critical points during pregnancy and perhaps also during a child’s early years plays a vital role in how the brain develops.

Levels of vitamin D in the women were also measured when they were 37 weeks pregnant.

Those with the the highest levels of vitamin D in their blood had children with had and were 0.5cm taller on average than children born in the darkest months.

University of Queensland professor John McGrath said low levels of vitamin D in early life have also been linked to the development of schizophrenia and other brain disorders like autism and bipolar.


“When you take vitamin D out of the brain’s developmental soup, you expose the brain to a whole range of developmental outcomes,” he said.


Low Vitamin D Can Make For a Tough Pregnancy

A link has been found between adverse health outcomes and vitamin D deficiency (levels less than 75nmol/L) resulting in complications such as gestational diabetes and preeclampsia in pregnant women and low birth weight in newborns.

In pregnancy, vitamin D also helps to develop your baby’s bones.

If you have a vitamin D deficiency it can affect the amount of calcium your baby has in their bones. In severe deficiency this can cause a bone deformity called rickets.


Emeds Comment

The main point to take away from this research is that its essential that you’re not deficient in any vitamins or minerals while pregnant, especially vitamin D.

If you are following a preconception program, you may also want to consider an Emed Mineral Status Profile or an Emed Nutrient Status Profile. Both profiles will tell you of any deficiencies, which could be treated and increase chances of conception.


Know Your Number – Vitamin D Testing

Every expectant mother should know their vitamin D levels.

A simple blood test will determine your Vitamin D Levels. You don’t even need to visit your GP, which means no boring waiting rooms.

Emed offers affordable Vitamin D testing through your local Pathology lab. For more information on Emed Vitamin D testing, click here.


Vitamin D3 status is assessed via a blood test measuring serum 25-hydroxyvitamin D [25(OH)D]. Optimal levels are:

Children: 25(OH)D > 50nmol/L

Adults: 25(OH)D > 75nmol/L however research shows that some measures of health may only improve at higher levels, > 100nmol/L

Talk to your Emed practitioner today about what your levels should be.


How to Increase Your Sunshine Vitamin 

As little as 30 minutes of early morning or late afternoon sunlight on your face, hands and arms two or three time a week can supply all the vitamin D you need. But some studies show that it’s preferable not to be wearing sunglasses or sunscreen for this period.

Both the skin and the retina of the eye may need a brief exposure for vitamin D to be produced. (Between the hours of 11 a.m. and 3 p.m.

If you’re over the age of 50, if you don’t get outdoors much or if you always wear sunscreen, you might want to consider vitamin D supplements.

Many experts recommend 1000 IU a day for people over the age of 50 and 1500 IU for those over the age of 70. For younger adults, 200-400 IU a day is probably sufficient.

Most supermarket and pharmacy-bought supplements are simply not strong enough, or contain the wrong type of vitamin D.

Investing in a premium, scientifically researched formula, like those on Emed’s Best Vitamin D Supplements, will ensure you are getting the best vitamin D supplement for your money and for your health.


Further Reading:



Knudsen TB, Thomsen SF, Ulrik CS, et al. 2007. Season of birth and risk of atopic disease among children and adolescents. J Asthma 44(4):257-60

Aghajafari F, et al “Association between maternal serum 25-hydroxyvitamin D level and pregnancy and neonatal outcomes: systematic review and meta-analysis of observational studies” BMJ 2013; 346: f1169

Lucas R, et al “Vitamin D sufficiency in pregnancy: Better evidence is required to establish optimal levels and need for supplementation” BMJ 2013; 346: f1675.