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By Asimina Tavaniotou

When are women mostly fertile?

Fertility is a combination of many factors.  For women, it varies during their menstrual cycle as they cannot get all days during their cycle. Women’s fertility greatly varies during their lives.  In addition, women of the same age have different chances of getting pregnant, due to different lifestyles and general health.

During the menstrual cycle there is the so called “fertile window” during which women can get pregnant.  Ovulation is the time that the oocyte is released from the follicle and can be fertilized by the sperm for about 24 hours. The sperm may be possible to fertilize the oocyte for about three days depending on the sperm quality. As a result, having regular intercourse at the time of ovulation and a few days before ovulation is the optimal time to achieve a pregnancy.

Women are born with a finite number of oocytes. Every month a number of oocytes becomes atretic and can no longer be used.  Oocytes of better quality are first used during a woman’s life. As a result, the number of oocytes is reduced with age, oocyte quality deteriorates and the chance of getting pregnant decreases. The chance of having a miscarriage also increases with age because of increased number of chromosomal anomalies in oocytes of older women.

Age is the most important factor related to a woman’s fertility and her chance of getting pregnant.  It is a fact that the chances of getting pregnant decreases with age although the exact time when it starts to happen may vary.  In general, women younger than 35 years of age have better chances of conceiving a child. Women during the third decade of their lives have even higher chances. Women younger than thirty have about 20%chances of getting pregnant every month. This is reduced to 5% by the age of 40. A fact not only for natural conception but also for assisted reproduction treatments.

However, women of all ages, even younger women, may improve their conception potential by improving their lifestyle.

Quitting smoking that affects oocyte quality but also harms the embryo during pregnancy is an important step.

Reducing caffeine and alcohol consumption may assist.

Improving diet (Mediterranean diet is an excellent example of a healthy diet) and having a BMI within normal range maximizes the chances of getting pregnant.

Obesity is related to reduced fertility and increased pregnancy complications.

Hormones play a key role in reproduction and a  normal thyroid function and optimal vitD levels improve the chances of getting pregnant and reduce miscarriage rates.

Asimina Tavaniotou

MD, MSc, PhD

Obstetrician – Gynecologist, Scientific Fellow, FIVI Fertility & IVF Center, European Interbalkan Medical Center

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