There is no universal “best month” to conceive a baby, and thank goodness, as timing conception to happen in a particular month is very difficult. There would be millions of disappointed or anxious couples every year if they all thought that one-month window was their golden opportunity. Even for a couple that does not have fertility problems (and about one in seven do), the chances of conceiving within a single monthly cycle are, at best, 30 percent.

There are studies and statistics about the most popular live birth months (August and September in the US, September in England and Wales, and July and August in Scotland, based on contemporary official information), and these do suggest that autumn and winter are the best seasons for success, but these statistics don’t factor in dates of conception, what the pregnancy experience was like for each couple, or the lengths of the pregnancies, so tracking these back to a best specific conception month is hard.

The most truthful answer is likely that the best month to conceive a baby is the right month for you and your partner, and every month of any pregnancy can be joyful under the right circumstances. If you have a particularly demanding or public job, the best timing of your pregnancy is any month that works perfectly for your schedule. If you have other children, you may be waiting for them to reach a particular age before growing your family, and it is always safest to allow at least 18 months between pregnancies, as research shows that shorter intervals can have negative health consequences for both mom and baby. Financial planning and the availability of a village to support you when there is a new arrival can also factor into the time of year that’s best for you to conceive.

If you have fertility concerns, the perfect month is any before the time you start to consider an invasive treatment like IVF or ICSI, or even the month in which one of those treatments proves successful.

Much is made in some camps about the superiority of going through late pregnancy—which can be very uncomfortable—in the summer months, though this discounts the number of mums who can’t bear being at their biggest when it’s warm or prefer to go through that first trimester morning sickness when it isn’t miserable outside. Every pregnancy is different, and you may find it useful to write a list of your own answers to the title’s question. What does “best” mean to you and your partner in this context?

Well, can the season impact my fertility?

Possibly. Both male and female fertility is influenced by age and any underlying health conditions, but your lifestyle behaviours (diet, sleep quality, exercise, alcohol and caffeine consumption, stress management, and smoking and drug use), are also extremely important, and these can change with the seasons. Many of us eat more heartily when it’s cold and lose weight when it is warmer outside, for example. Low blood iron is more common in women of reproductive age because of periods, and this condition can impact fertility seasonally. If you tend to go vegan or vegetarian at certain times of the year, for example, it can impact your iron levels. Straightforward blood tests should show if you need to supplement. Read more about when and how to take your iron supplements.

There may be times of the year in which you feel closer to your partner or just feel like having sex more often (e.g., around Christmas and Valentine’s Day), which greatly increases your chances of conception.

However, if you simply stick to your regular diet, exercise, etc. regardless of time of year, seasons won’t be affecting your fertility for lifestyle reasons.

Low Vitamin D levels that come through lack of sun exposure in some climates in winter are thought to affect your fertility, though supplementing your diet should easily take care of this. It can be hard to assess whether your vitamin D is low independently, as the symptoms—e.g., muscle weakness, hair loss, pins and needles—won't be the same for everyone and can be attributed to other problems, so it’s important to get your levels checked with a specific blood test. If you’re worried and can’t get tested, supplementing anyway is usually safe, as your body will simply excrete what it doesn't need. Don’t take anything without medical advice if you suspect you’re already pregnant, even if it’s an over-the-counter supplement.

Temperature also plays a role in fertility, and there is some evidence that conception is less likely in hotter climates in the summer. This is thought to be due to how heat impacts both egg and sperm quality, though regular access to air conditioning has also been shown to positively impact your chances if you’re somewhere hot.

Light impacts human psychology, and our mental health is known to influence our likelihood of conception. However, proper environmental support during darker months—well-lit living and professional spaces, good nutrition, and proper healthcare—in most developed countries is likely to compensate for any negative effects associated with daytime darkness.

Studies show that reproductive hormones in both men and women are impacted by the seasons, with some women ovulating less and having longer menstrual cycles in winter and some men producing less sperm at the same time of year. However, as reproductive hormones are influenced by so many factors (age, overall health, stress, etc.) and low fertility in winter appears to conflict with peaking live birth figures in the autumn, it is hard to conclude that winter is a bad time to try to conceive.

But I really want my baby to be born in a specific month...

The only way you can be sure of a baby being born in a specific month is to plan an elective caesarean, and even then the health of your pregnancy, your baby, and yourself would be so important to your healthcare team that you would need to be quite far along to get the best advice. Plus, due dates are always estimates. Even if you could time the month of your conception, there’s no guarantee that a natural birth will happen exactly nine months later, and a planned induction can take days to progress to labour. We are not saying you can’t try, though; there’s just no need to be too disappointed if it doesn’t happen. The odds are against you. Good luck!

For more advice on successfully conceiving a baby, check out Unii’s Preconception Journey with award-winning obstetrician and gynaecologist Dr. Shree Datta.

Which is the best month to conceive a baby?

How do the seasons compare, baby-making potential wise?