1. Weight

Being overweight or obese reduces male and female fertility and, in women, being significantly underweight can affect regular ovulation. Women who undertake rigorous athletic training may experience irregular periods.

2. Alcohol and smoking 

Too much alcohol can damage the quality of a man’s sperm, therefore decreasing the chance of fertilisation, and can also decrease a woman’s fertility. Couples should follow the chief medical officers’ guidelines and limit their alcohol intake. The safest approach for women is to not drink alcohol at all, and men should not exceed 14 units per week, ensuring they have at least two alcohol-free days. Research suggests that smoking may also adversely affect fertility in both men and women, and support to quit smoking should be offered to all couples hoping to conceive.

3. Stress 

Day-to-day stresses can contribute to a loss of libido (sex drive) and, in severe cases, can even affect ovulation and fertility.

4. Medicines and drugs 

Some prescribed medication, such as those administered during chemotherapy, can affect ovulation and sperm production. In women, antipsychotic medicines can sometimes cause missed periods, while in men, long-term use of anabolic steroids can affect sperm count and mobility. Illegal drugs also have detrimental effects.

5. Environmental factors 

Exposure to certain hazardous chemicals can cause fertility issues.