In the United States, November and December are the two months of the year that you're most likely to get pregnant. Why? Is it due to some complex scientific theory or physiological differences? No! It's because you'll have more sex! Think about it, in the hot summer months we're out enjoying the sunshine, swimming in the sea, and desperately pushing our partners away as we try to cool down. In the winter, we're clinging to each other for warmth, in front of the roaring fireplace with a glass of wine.. and we all know where that leads!

You don't often hear much about the month of conception itself though, as once the deed is done, it's all about looking to the future, and thinking about the month the baby will be born. Will you need a summer romper or a thick winter coat? The conception month is often just pushed to the back of the mind, but it could actually be more important than we think. Could the month of conception mean ourselves and our babies are more susceptible to health conditions?


Preeclampsia is a potentially life threatening condition for both mom and baby, and is associated with high blood pressure. Exactly what causes the condition is unknown, but based on research into a link between preeclampsia and conception month, we're able to take a reasonable guess as to some aspects that may heighten the risk.

Studies have found that, in the west where our seasons are typically a warm summer and a cold, or cooler, winter, preeclampsia is much more likely to occur in babies conceived in the spring or summer, and born in the fall or winter. Research shows a difference of 0.9 percent between summer conception and winter conception babies, which although small, is enough to make us wonder why. The theory is that as the temperatures cool and fresh produce becomes scarce, both mom and baby suffer nutritionally which not only affects development, but also lowers the immune system, making us vulnerable to winter bugs. This theory is backed up by evidence suggesting that preeclampsia rates are much higher in Scandinavia and the north than they are in the warmer south. The condition has long been thought to stem from poor diet and a weakened immune system, and this theory strengthens the notion.


Autism, and, more specifically, its cause, is a very controversial topic. Much like cancer, various "studies", and I use the term loosely, have associated autism with absolutely everything under the sun, ranging from vaccinations and obesity to nasal sprays and even bad parenting! The truth is, we don't know why some children develop autism and some don't, but some scientists have discussed possible causes based upon conception month.

Children conceived between December and March, in the winter, tend to have the highest vulnerability to autism. Interestingly, these months are when influenza outbreaks are common. Could a simple viral infection during the early months when the baby is developing neurologically cause autism? There have been very few studies carried out looking at viral infections in relation to the condition, but this is certainly something that warrants further investigation. Another possible cause that stems from the information that winter conceptions carry more risk is the increase in pesticides and other artificial chemicals used on crops to protect them in the cold conditions. A cause of autism? Who knows. A lead worth examining? Absolutely.


As with autism, it's very difficult, no, impossible, to say with any certainty "this is what causes schizophrenia", but there is a medically accepted trend that schizophrenics and those with other mental health and neural tube disorders, are often conceived in summer and born in the winter, especially those who come from families with no previous developmental or mental health concerns. Many studies cite a 10 percent increase in risk for winter born babies.

A theory put forward as to a cause for this risk percentage is maternal oxidative stress. Oxidative stress is when our bodies change in reaction to environmental factors, such as bright sunlight in the summer months, and is thought to affect neural tube development, specifically the closure of the tube. The neural tube typically closes when you're just one month into your pregnancy, so it's natural to consider the outside factors at the time of conception. Bizarrely, the same theory is given for left handedness, as the two are believed to stem from the same neurological anomaly.


Clubfoot is a condition which means a baby is born with one, but usually both feet twisted so that they do not point straight. As well as visual issues, there are also many practical issues, the most significant being that children with severe clubfoot may not be able to walk. Fortunately, the condition can be successfully treated with surgery during infancy. The cause of clubfoot is unknown, although the most common explanations are smoking during pregnancy and a family history of the condition, but is there another likely cause?

Research suggests that babies conceived in the summer are more likely to suffer with clubfoot, leading scientists to wonder if diseases that are rife in the summer months could play a part in the development. The most promising lead is the enterovirus which does the rounds during the hot summer, and causes a range of conditions relating to the stomach, the brain, and the lungs. Researchers believe that these viruses could contribute to physical deformities such as clubfoot.

Should I Be Worried?

Absolutely not! As you can see, there are suggestions that having a baby in all seasons can increase health risks, but if it was really a concern, there would be no healthy babies! In addition, if you do a little digging, you'll also find studies that completely contradict the research mentioned above. For example, although the above shows that babies conceived in winter are more likely to develop autism in the United States, the results for the UK, where the climate is slightly colder on average but generally not massively different, are totally flipped upside down, with evidence supporting a higher risk for summer conceived babies. Whatever month you conceive, just be sure to stay active and healthy to give your baby the best start in life.