Understanding the Relationship Between Age and Pregnancy: Optimizing Your Fertility Journey

Fertility Declines with Age

In Japan, marriage and childbearing are increasingly delayed. From a medical perspective, pregnancies after age 35 are classified as “advanced maternal age,” which can bring higher risks, including decreased fertility and higher miscarriage rates. Here, we examine how age affects pregnancy rates and the specific risks associated with advanced maternal age.

For healthy individuals without reproductive health issues, engaging in intercourse around the time of ovulation yields a natural conception rate of 20–25% per cycle. Continuously trying to conceive for a year brings the chances of conception to 80% within six months and 90% within a year.

However, while the natural conception rate per cycle remains around 20–25% through the early 30s, it drops to 18% by age 35, falls to 5% in the early 40s, and drops close to 1% after age 45. On a yearly basis, women in their 20s have nearly a 100% chance of conception, but this rate drops significantly to around 60% by their late 30s.

Risks Associated with Advanced Maternal Age

With age, both the likelihood of conception and the risk of miscarriage increase. Miscarriage risk stays around 20% through the late 30s but rises sharply after age 40, reaching more than double the risk observed in women in their 20s.

Risks of Pregnancy at Advanced Maternal Age

Medically, pregnancies after age 35 are considered “advanced maternal age.” While it is not uncommon today for first-time mothers to give birth after 35, advanced maternal age comes with additional risks that require careful consideration.

• Increased Risk of Premature Birth, Miscarriage, and Complicated Labor

As women age, the risk of miscarriage and complications during delivery rises. The increase in miscarriage risk is often due to a higher frequency of chromosomal abnormalities in eggs. Moreover, as the birth canal, blood vessels, and cervix gradually become less flexible, the chances of experiencing a complicated labor increase. Delayed or difficult delivery can impose greater physical strain on the mother.

• Higher Risk of Pregnancy-Related Hypertension and Gestational Diabetes

Conditions like pregnancy-induced hypertension and gestational diabetes also become more likely with age. Pregnancy-induced hypertension, a condition in which high blood pressure during pregnancy damages organs like the kidneys, is one such risk. Gestational diabetes, a condition where blood glucose levels become elevated due to pregnancy, can lead to excessive amniotic fluid and other complications, potentially impacting the baby’s health.

• Increased Chance of Chromosomal Abnormalities

The probability of chromosomal abnormalities, such as Down syndrome, also rises with maternal age. The likelihood of Down syndrome is approximately 0.1% for women in their 20s, 0.3% in their 30s, and 1% in their 40s, demonstrating a clear age-related increase.

Average Fertility Efforts and Timelines

According to the Ninkatsu White Paper 2019 by Rohto Pharmaceutical, most individuals begin fertility efforts in their late 20s to early 30s, with approximately 60% starting within this age range. A 2014 study by MTI Co., Ltd.’s LunaLuna Family found that the majority, 28.8%, conceived within three months of trying to conceive, followed by 25.6% conceiving within four to six months, indicating that over half of individuals achieve pregnancy within six months.

However, uterine and reproductive health issues tend to increase in the 30s and 40s, so these timeframes should only serve as general guidelines.

Insurance Coverage for IVF is Available for Women Under 43

Since April 2022, insurance coverage for infertility treatments, including IVF, has alleviated some of the financial burdens associated with fertility treatments. However, there is an age limit for insurance eligibility, with coverage only available for individuals who begin treatment before age 43.

Additionally, the number of embryo transfer cycles covered by insurance depends on age. Women under 40 are eligible for up to six embryo transfers per child, while women aged 40 to 43 are eligible for up to three transfers per child.

Early Action for Infertility Treatment is Recommended

As age increases, so do the risks of reduced fertility, miscarriage, complicated labor, and potential health impacts on the child. Insurance coverage for IVF is now available but has both age and cycle limits. Furthermore, age-related conditions affecting the uterus become more prevalent, potentially delaying infertility treatments.

If you wish to conceive, it is essential to take action promptly.