Factors in Fertility
Fertility describes the ability to conceive naturally, relying on healthy eggs, sperm and the formation of a viable embryo. Modifying lifestyle choices allows us to control some fertility factors, but environmental surroundings and genetics still play key roles. Occasionally, unexplained infertility arises wherein no specific cause is identified.
Infertility, which affects between 10 and 15 percent of couples in the United States, is defined as having regular, unprotected sexual intercourse for one year without it resulting in pregnancy. Experts suggest receiving an evaluation after six months if you are over 35 and right away if you are over 40. Fortunately, several fertility options exist for couples who struggle to get pregnant, and seeking help early can improve your chances.
An overview of fertility
Female fertility is directly related to age due to a natural decline in egg numbers and quality over time. Some lifestyle habits, medical conditions and environmental factors can also contribute to female infertility. Surgery can remove uterine polyps or fibroids, fix damaged or blocked fallopian tubes and treat endometriosis, which are some of the potential underlying causes of infertility.
Male fertility issues are a significant contributor to infertility in couples, accounting for about 40 percent of infertility cases. A sperm analysis will test for underlying causes such as:
- Asthenozoospermia: This translates to poor motility (movement); sperm that swim erratically or don't swim at all
- Oligozoospermia: Low sperm count, defined as less than 20 million sperm per milliliter of semen
- Teratozoospermia: Abnormal morphology (shape) of the head, tail or midsection of the sperm, which impairs its ability to fertilize an egg without medical assistance
Reference values for sperm analysis are based on data from the World Health Organization (WHO). Male infertility can also result if the tubes responsible for carrying the sperm to the testicles are blocked. Swollen veins in the scrotum can cause more body heat to reach the testicles, which affects sperm production and may impede fertility, and may be treated with surgery.
Genetic factors that can impact fertility
Genetics plays a role in both the initial ability to conceive and the likelihood of maintaining a healthy pregnancy. Inherited genetic mutations can affect both female and male fertility.
In the developing fetus, chromosomal abnormalities are a common cause of early pregnancy loss or miscarriage. About 50 percent of embryos that don’t survive beyond the first trimester are believed to have chromosomal issues. Under ideal circumstances, the sperm and the egg each contribute 23 chromosomes for a total of 46 in the fertilized egg. If this number is higher or lower, developmental issues can prevent the pregnancy from progressing.
Environmental factors that can impact fertility
Beyond the genes we inherit, acquired genetic mutations also affect fertility. Research increasingly points to radiation as a cause of DNA damage to sperm in the testes. Sources may include everything from microwaves to laptops and cell phones. While we may not be able to modify our exposure to all radiation sources (particularly Wi-Fi signals), making small changes, like not carrying your cell phone in your pants pocket, may help.
Cancer treatments can also affect fertility for men and women. You can discuss preventive steps to preserve your fertility before undergoing treatment, like harvesting your sperm or eggs and medically storing them for future use.
Various environmental toxins are associated with poor reproductive health. Epidemiological data suggest bisphenol A (BPA), dioxins, fracking chemicals, phthalates and pesticides can negatively impact semen production and female fertility. Issues like polycystic ovarian syndrome (PCOS) and preterm birth are more common with exposure to these toxins and high air pollution areas.
Making an effort to choose natural products can limit your exposure. Until more studies are performed, following a healthy lifestyle (including a diet high in antioxidants) may be the best defense currently available.
Lifestyle factors that can impact fertility
When struggling with infertility, it's essential to focus on what you can control. Most lifestyle habits that negatively affect our general health threaten fertility. Smoking, substance abuse and being over- or underweight are common causes of infertility. For women, eating disorders and overexercising can lead to difficulties in becoming pregnant.
Scientists have proposed various ways smoking reduces male fertility, including impaired oxygen intake, faster testosterone metabolism and exposure to toxins in cigarettes. Although the exact mechanism remains unclear, the American Society of Reproductive Medicine found a 22 percent higher rate of abnormalities in sperm analysis tests for smokers versus nonsmokers. This association is dose-dependent, suggesting there are still fertility benefits to cutting back on smoking even if you don’t quit altogether.
Both firsthand and secondhand smoke can negatively impact female fertility and pregnancy outcomes. Some of the effects of smoking on female reproductive health include:
- Delayed implantation
- Early menopause
- Ectopic pregnancy risk
- Heavy menstrual bleeding
- Higher androgen levels (male hormones)
- Lower ovarian reserves
- Poor-quality oocytes (an immature egg cell)
- Reduced estrogen and progesterone
Due to its influence on multiple reproductive organs, smoking is associated with a 60 percent increased female infertility risk.
Alcohol, marijuana and anabolic steroids are known contributors to male infertility. If you're prescribed medication for high blood pressure, depression or to treat bacterial infections, talk to your doctor about how this may affect your fertility.
Illicit drug use affects fertility and leads to adverse pregnancy outcomes. Animal studies suggest cocaine and methamphetamine interfere with female fertility by influencing progesterone, estradiol and luteinizing hormone levels. Regular heroin use results in a loss of a normal menstrual cycle, which usually returns when drug use is discontinued. If you’re battling an addiction, getting help before trying to conceive will help set the stage for a healthy pregnancy.
Practicing safe sex is another crucial way to protect fertility. Sexually transmitted diseases (STDs) can lower sperm count and can also permanently impact female fertility if left untreated.
Gonorrhea and chlamydia can produce pelvic inflammatory disease, which damages the uterus, fallopian tubes and surrounding tissues. In 2018, the United States saw 4 million new cases of chlamydia and 1.6 million gonorrhea cases. Since most people are asymptomatic, regular testing is essential to ensure timely treatment before permanent damage occurs.
How to track ovulation
Pregnancy is only possible during specific times of the menstrual cycle. Understanding the different stages of the menstrual cycle can help you predict the timing of egg release (ovulation) and improve your chances of getting pregnant.
Day one of the menstrual cycle is when bleeding begins. Timing varies slightly from person to person, but the average cycle lasts 28 days. Ovulation typically occurs during the midpoint, which is two weeks after day one (on day 14). After release, the egg travels down the fallopian tube, where it remains for potential fertilization for 24 hours.
Since sperm can live for up to five days within a woman's body, it's possible to get pregnant when having sex between five days before or one day after ovulation. Most experts suggest having intercourse either every day or every other day during your fertile window.
There are various methods to track ovulation, including:
- Basal body temperature method: Your body temperature at rest increases slightly (0.5 to 1 degree Fahrenheit) from the time of ovulation until the next menstrual cycle.
- Cervical mucus method: Vaginal discharge increases and becomes thinner on the days leading up to ovulation, so detecting these changes can help you predict the more fertile days of the month.
- Standard days method: If you have regular, consistent cycles, you can use the standard days method to count out when ovulation will occur and determine the days you’ll be most fertile.
You can also check your ovulation using test strips that detect luteinizing hormone in the urine (a sign ovulation is about to occur). Several smartphone apps are available to assist with tracking. If you’re interested in learning more about natural family planning, talk to your OB-GYN about local resources or workshops you can attend.
With any of these methods, miscalculations are possible. For instance, your basal body temperature might be slightly elevated if you're fighting off an infection, and cervical mucus can change in response to intercourse or medications. While these methods may help you to conceive, they shouldn’t be relied on to prevent pregnancy.