Female age has been shown in multiple studies to be a predictor of poor reproductive success with assisted reproductive technology (ART), resulting in decreased fertility rates, increased miscarriage rates, and decreased embryo implantation rates. This decline in female reproductive function can be explained partly by an increase in chromosomal anomalies observed in oocytes and embryos. As we age, many aspects of our bodies and health change. This includes many subtle but important changes in the reproductive process for women. The impact of age on fertility is increasingly significant as more women choose to delay childbearing until later in life.
Female Fertility and Age
The most important factor for all women and their partners to understand is that a woman’s reproductive potential declines with age. When this decline begins, often around age 30, most women do not even realize that it is happening. Even though a woman may continue to have regular menstrual cycles until she reaches menopause, the ability to have children may be lost 7 to 12 years prior to menopause. Nearly 1/3 of women age 35 or older will have problems with fertility. And more than 70% of women over age 40 are unable to become pregnant naturally. In addition to increased difficulty with fertility, a woman’s chance of having a miscarriage also increases with age. The main factor associated with infertility in women is egg quality. As women age, their egg quality declines. The process of declining fertility is universal and increases with age. However, the timing of this phenomenon is variable and may begin to occur in young women. Even young women need evaluation for decreased ovarian reserve. Any patient who has tried to conceive a baby for a year without success should consult a physician. If a woman is over age 34, she should consult a fertility expert after trying to conceive for six months.
Infertility Evaluation and Management
For women of advanced reproductive age, infertility assessment and treatment require a more proactive and targeted approach due to the natural decline in egg quality and ovarian reserve. Medical evaluation is generally recommended after six months of unsuccessful attempts to conceive for women over 35, and after just three months if the woman is over 40. The diagnostic process often includes ovarian reserve testing through bloodwork, such as anti-Müllerian hormone (AMH) levels and follicle-stimulating hormone (FSH) measurements, as well as transvaginal ultrasounds to assess antral follicle count. Additional assessments may examine uterine health, fallopian tube patency, and male partner fertility. Based on these findings, treatment options vary. Some women may benefit from ovulation induction medications or intrauterine insemination (IUI), particularly if ovulation or cervical factors are contributing to infertility. However, in many cases, in vitro fertilization (IVF) is recommended as it offers higher success rates for older women. For those with severely diminished egg quality, donor eggs can significantly improve outcomes. Adjunctive approaches, such as preimplantation genetic testing (PGT), may also be recommended to reduce the risk of chromosomal abnormalities. Because time is critical, seeking specialist advice early allows women to explore all available options and optimize the chances of conception.
Assisted Reproductive Technologies
Assisted reproductive technologies (ART), including in vitro fertilization (IVF) and egg donation, play a significant role for women facing age-related fertility decline. These approaches provide valuable options for women who wish to conceive later in life, but outcomes are closely linked to the age and quality of the eggs used in treatment.
Egg Quality and Quantity
A woman’s age is one of the most significant factors influencing both the quality and quantity of her eggs, directly shaping fertility potential and the likelihood of conception. Women are born with a finite number of eggs, which gradually decline over time. By puberty, only about 300,000 to 500,000 remain, and throughout her reproductive years, only around 300 to 500 eggs will be released through ovulation. The most fertile years are typically in a woman’s 20s, when both the number and quality of eggs are at their peak. As age advances, particularly after 30 and more notably after 35, the number of viable eggs decreases at a faster rate. By the early 40s, the ovarian reserve is significantly diminished, and egg quality has often declined to the point where the probability of natural conception becomes very low. Egg quality refers not only to the ability of the egg to be fertilized but also to its chromosomal health. Younger eggs have a much lower risk of chromosomal abnormalities. In comparison, older eggs are more likely to carry issues such as aneuploidy, where the egg has too few or too many chromosomes. This increased risk of chromosomal abnormalities with age not only reduces the chances of successful fertilization and implantation but also raises the likelihood of miscarriage and genetic disorders such as Down syndrome. As a result, women in their late 30s and 40s face a dual challenge: a reduced number of eggs available and a higher proportion of eggs that may be genetically abnormal. This natural decline in fertility explains why it generally takes longer for women over 35 to conceive, even if they are otherwise healthy.
Advances in reproductive medicine, such as in vitro fertilization (IVF), egg freezing, and the use of donor eggs, have provided options to address these age-related declines, but they cannot fully restore the natural fertility potential of younger years. For instance, egg freezing at a younger age preserves higher-quality eggs, which can later be used when natural fertility has diminished. IVF success rates are also closely tied to age, with women under 35 experiencing much higher success rates than women over 40. In practical terms, this means that while modern medicine can extend reproductive possibilities, biology still sets clear limitations. Understanding how age affects egg quality and quantity helps women and couples make informed decisions about family planning, timelines, and the use of fertility treatments when necessary. This interplay between age, egg health, and conception underscores why discussions about fertility preservation and proactive reproductive health are becoming increasingly important for women who wish to delay motherhood.
The Impact of Male Age on Fertility
While much of the conversation around reproductive aging focuses on women, it’s important to recognize that male age can also influence fertility, albeit typically to a lesser degree. Unlike women, who are born with a finite number of eggs that decline in both number and quality over time, men continue to produce sperm throughout their lives. However, this ongoing production does not mean male fertility is immune to the effects of aging. As men age, especially after the age of 40, subtle yet significant changes can occur in sperm quality and reproductive potential. One of the most notable effects of advancing male age is a gradual decline in semen parameters. Sperm count, motility (the ability of sperm to move efficiently), and morphology (the shape and structure of sperm) can all diminish as men age. While many men remain fertile into their 50s and beyond, these age-related changes can reduce the likelihood of conception, particularly when combined with female partner age or other fertility factors. For example, studies have shown that couples in which the male partner is over 40 may experience longer times to conception and lower overall pregnancy rates compared to couples with younger male partners.
In addition to affecting the chances of conception, increased male age is associated with a higher risk of genetic mutations in sperm. As men age, the number of cell divisions required to produce sperm increases, raising the risk of DNA errors. This can lead to a greater likelihood of certain genetic conditions in offspring, such as an increased risk of autism spectrum disorders, schizophrenia, and some rare genetic syndromes. Although the absolute risk remains low, the association is well-established and becomes more pronounced as paternal age advances.
Older men may also experience changes in sexual health that can impact fertility. Conditions such as decreased libido, erectile dysfunction, and lower testosterone levels become more common with age and can interfere with the ability to achieve pregnancy. Furthermore, chronic health issues tend to increase with age and can further impair male reproductive function. Despite these factors, it’s important to emphasize that male fertility decline is generally more gradual and less predictable than in women. Some men maintain normal reproductive potential well into their later years, especially if they are in good overall health. Nonetheless, for couples experiencing difficulty conceiving, it is important to consider the age and health of both partners. A comprehensive fertility evaluation should include assessment of male factors, regardless of age.
Fertility Preservation Options
For women considering delaying childbearing, understanding fertility preservation options is increasingly important. As age-related fertility decline is a natural process, proactive planning can help maintain future reproductive choices. Several methods are available to help preserve fertility, each with its own considerations, benefits, and limitations. Below are four key options and factors to consider for women interested in delaying pregnancy.
- Egg Freezing (Oocyte Cryopreservation): Egg freezing involves retrieving multiple eggs from the ovaries and freezing them unfertilized for later use. This technique allows women to preserve their eggs at a younger, healthier age, when egg quality is typically higher. When ready to conceive, the eggs can be thawed, fertilized, and implanted via in vitro fertilization (IVF). It is important to note that the success of egg freezing depends on the woman’s age at the time of freezing, with higher success rates seen in women under 35.
- Embryo Freezing: This is similar to egg freezing, but the eggs are fertilized with sperm before being frozen. This option is generally chosen by women who have a partner or are using donor sperm and want to maximize their chances of a future pregnancy. Embryo freezing has a longer track record of success compared to egg freezing, as embryos tend to survive the freezing and thawing process better. However, it does require making decisions about the use and disposition of embryos in the future.
- Ovarian Tissue Freezing: Ovarian tissue freezing is a newer and less common method, typically reserved for women who need to undergo treatments (such as chemotherapy) that may damage the ovaries. In this procedure, a portion of ovarian tissue is surgically removed and frozen for later transplantation. When the woman is ready to conceive, the tissue can be reimplanted to restore fertility.
- Lifestyle and Medical Considerations: Deciding to delay childbearing and pursue fertility preservation requires careful consideration of personal, medical, and financial factors. Women should consult with a fertility specialist to assess their individual risks, understand the costs and success rates of preservation techniques, and discuss potential health impacts. Insurance coverage may vary, and not all preservation methods are suitable for every individual. Early planning and informed decision-making are essential to optimize the chances of a healthy pregnancy in the future.
Fertility preservation offers valuable options for women who wish to delay childbearing due to personal, career, or medical reasons. By understanding the available methods and carefully weighing the considerations, women can make informed choices that align with their life goals and reproductive plans.
Pregnancy Risks with Advancing Age
As more women choose to delay childbearing, understanding the potential risks and complications associated with pregnancy at older maternal ages becomes increasingly essential. Advancing maternal age can affect both the mother and baby, leading to unique health considerations that should be carefully discussed with a healthcare provider.
- Increased Risk of Chromosomal Abnormalities: As women age, the risk of chromosomal abnormalities in the baby, such as Down syndrome (trisomy 21), rises significantly. For example, the likelihood of having a baby with Down syndrome increases from about 1 in 1,250 at age 20 to 1 in 86 at age 40. These abnormalities can lead to developmental delays, health problems, and may require additional prenatal screening and genetic counseling.
- Higher Rates of Pregnancy Loss: Older maternal age is associated with an elevated risk of miscarriage and stillbirth. The rate of miscarriage increases steadily after age 35, reaching up to 50% by the mid-40s. This is largely due to declining egg quality and increased rates of chromosomal abnormalities. Stillbirth risk also rises after age 35, prompting recommendations for increased monitoring and, in some cases, earlier delivery.
- Greater Likelihood of Pregnancy Complications: Women over 35 are more likely to develop pregnancy-related complications such as preeclampsia (a dangerous increase in blood pressure), gestational diabetes, and placenta previa. These conditions can pose significant health risks to both the mother and baby, sometimes requiring early delivery or specialized care throughout pregnancy to manage symptoms and prevent adverse outcomes.
- Increased Chance of Preexisting Health Conditions Affecting Pregnancy: Advancing age often correlates with a higher incidence of chronic health conditions like hypertension, diabetes, or thyroid disorders. These preexisting conditions can complicate pregnancy, increasing the risk of poor maternal and fetal outcomes. Women are encouraged to have a thorough preconception health assessment and to manage chronic illnesses before becoming pregnant to optimize safety.
- Higher Risk of Multiple Pregnancy: Older women are more likely to conceive twins or higher-order multiples, both naturally and as a result of fertility treatments. Multiple pregnancies carry increased risks, including preterm birth, low birth weight, and complications during delivery.
- Elevated Risk of Delivery Complications and Cesarean Birth: Women of advanced maternal age are at greater risk for complications during labor and delivery, such as prolonged labor, fetal distress, and the need for cesarean section. Cesarean delivery itself carries additional risks, including infection, bleeding, and longer recovery times. Careful birth planning and regular prenatal care can help manage and mitigate these risks.
Being informed about these potential challenges allows women and their healthcare providers to take proactive steps to promote the best possible outcomes for both mother and baby.
Age plays a powerful role in shaping fertility, and understanding its impact allows women and couples to make informed choices about their reproductive journeys. While natural fertility declines steadily after the early 30s and accelerates after 35, advances in reproductive medicine offer meaningful options to overcome many of these challenges. From egg freezing and IVF to donor egg use and preimplantation genetic testing, modern interventions can improve the chances of building a family, even when age is a barrier. Still, biology sets important limits, and outcomes are best when proactive steps are taken early. Seeking medical guidance after six months of trying to conceive at age 35 or older ensures that issues are identified and addressed quickly, maximizing the possibility of success. Male age also contributes to fertility outcomes, reminding us that both partners benefit from evaluation. Combining medical knowledge with timely planning empowers individuals to approach family building with greater confidence, clarity, and opportunity.