A woman is 40 years old and a heavy smoker. She has a single sexual partner but has very irregular menstrual cycles. She wants a highly reliable contraceptive. Which method would be the best recommendation?
a. The rhythm (calendar) method
b. A diaphragm and spermicide
c. An ovulation suppressant
d. A spermicidal suppository

A diaphragm and spermicide would be best recommended contraceptive

Explanation:

For a woman who is 40 years old, a smoker, and with irregular menstrual periods, the diaphragm with spermicide method would be the best option for contraception and prevention of pregnancy.

The natural rhythm calendar method is based on tracking the fertile days of the menstrual cycles and the length of menstrual cycles. Hence, for a woman with irregular menstrual periods, this method may not be successful in preventing pregnancy.  

Ovulation suppressant may not be ideal for woman over 40’s and especially with smoking, since these are hormone based and may lead to osteoporosis or weak bones. These also induce thromboembolism and with her smoking history, this method would be risking her heart health.

Spermicidal suppository may fail due to dryness of vagina due to age of the woman.

A diaphragm with spermicide is a barrier type of contraceptive method that is highly effective and more than 95% successful in preventing pregnancy. This is a silicone cup that is fitted at the cervix and acts as a barrier for the sperm to enter inside the cervix. Additionally, when spermicide is added to it, motility of the sperm towards the egg is inhibited to a great extent and thus preventing pregnancy.