Prescribed drugs
Both prescribed and recreational drugs can affect fertility and cause problems for pregnancy. Women should avoid drugs known to cause defects in the baby: these include retinoids (Vitamin A drugs sometimes prescribed for acne), warfarin, lithium, danazol, phenytoin, carbamazepine and valproate. If you are taking any of these and wanting pregnancy, it is best to discuss it with your GP first rather than just stopping them. Heavy use of strong aspirin-like drugs such as Ibuprofen are best avoided if you are trying for pregnancy, as they can interfere with ovulation. Drugs known to interfere with sperm production include: tetracyclines and cimetidine, an anti-ulcer drug and allopurinol, which is used as a treatment for gout. Propranolol, methyldopa, chlorpromazine and some antidepressants can cause erection difficulties.
Recreational drugs
Cannabis, cocaine and anabolic steroids are all known to significantly reduce the sperm count and affect fertility. Cannabis can also interfere with ovulation in women. Smoking is detrimental to a woman's fertility, reducing the chance of pregnancy by as much as 50-70% per cycle. There is also an increased risk of miscarriage in smokers. For men, smoking reduces the average sperm count by around 15%, also affecting the swimming ability of the sperm. Although studies have not specifically found that smoking in men delays conception or affects fertility, it would be sensible to give up in view of the health benefits. There is no strong link between alcohol intake and fertility, however it is well recognised that alcohol can affect fetal development and women should limit intake to no more than one unit once or twice a week.
Helpful medications
If a woman has an otherwise healthy diet, there is no need for additional multivitamin tablets. There is now very good evidence that taking 400 micrograms of folic acid per day when becoming pregnant reduces the risk of neural tube disorders such as spina bifida. In women who have had a previous pregnancy affected by this condition or who are epileptic and on medication, this should be increased to 5mg per day.
If folic acid wasn't taken before conception, it should be started as soon as possible when pregnancy is discovered before the end of the first trimester.