Having a baby isn’t a given. One in six couples will have difficulty conceiving, and many will secretly wonder if they are alone in having difficulty. I'm here to tell them, they are not. Over 3 million U.S. couples have found out that even though they are healthy, they can’t have a baby.

There are many things that couples can do to boost their chances for conception. Here are 12:

1. Get an early start. If you're ready to have a baby, try to have a child as soon as possible. Not every woman is in a position to have a baby in their twenties, but for those waiting for the perfect moment, earlier is better. After age 35, if pregnancy does not occur in 6 months, make an appointment with a specialist.

2. Both partners should keep their weight to within 15% of their ideal weight. Being either underweight or overweight can slow things down.

3. Maintain a good exercise schedule, but don’t overdo it. Running more than 30 miles per week or similar exertion can have a negative effect on fertility.

4. Quit smoking

5. Maintain a healthy diet with plenty of fruits, cruciferous vegetables and leafy greens. Kelp, soy (particularly black soybeans and tofu), almonds, walnuts, whole grains and wheat germ are also good foods to eat. Avoid high loads of sugars and carbohydrates, including sodas.

6. Begin taking a multivitamin with iron and calcium. Start three months before you want to conceive to be sure levels are high enough. Men should consider a multivitamin with antioxidants to help sperm.

7. Maintain a healthy vaginal pH of approximately 4.5. Many factors, like frequent sex, different sexual partners, menstrual flow, tampons or even douching can increase vaginal pH. An over the counter pH solution, such as RepHresh, can help maintain a healthy vaginal pH.

8. Avoid vaginal lubricants just before intercourse. Most contain antibacterial agents that can have a negative effect on sperm. Natural lubrication as a result of plenty of clitoral stimulation or vaginal moisturizers are reported not to affect sperm viability in patients.

9. Avoid antihistamines, especially in midcycle. They can dry out cervical secretions.

10. Acupuncture has been shown to be beneficial for lower sperm counts. One study showed acupuncture done 25 minutes before embryo transfer for in vitro fertilization yielded a significant increase in pregnancy rates.

11. Reduce stress. Relaxation techniques, yoga, biofeedback and making time for oneself can do the trick. Sex shouldn’t be a chore, either. Take time to make time.

12. Finally, the obvious. Be sure to time sex around midcycle—about day 10 to 12 in a typical 28-day cycle. Sperm live longer than the egg so be sure the sperm, i.e. your husband, is available a day or two before ovulation.

Dr. Machelle Seibel is a Professor of Obstetrics and Gynecology at the University of Massachusetts, and Editor in Chief of Sexuality, Reproduction and Menopause, a journal of the American Society for Reproductive Medicine.