By Dr Fessy Louis T
The first In Vitro Fertilisation (IVF) baby, Louise Joy Brown, was born on July 24, 1978. Since then, millions of IVF babies have been born. IVF, or in vitro fertilization, means the fusion of egg and sperm outside the body. We stimulate the ovaries to produce multiple eggs with the help of medications and give medicines to prevent ovulation, and when eggs are mature before ovulation, we retrieve them outside the body and fuse them with the sperm.
The success of IVF mainly depends on the quality of eggs and sperm and, ultimately, the quality of embryos. Female age is the most important determinant of the quality of eggs. Male age also affects the quality of sperm, but lifestyle factors and co-morbidities play a more important role.
Female Age
As women age, both the quantity and quality of their eggs decrease, which in turn affects their chances of achieving a successful pregnancy or live birth through IVF treatment. The most favourable success rates with in vitro fertilization are typically seen in women in their 20s and 30s.
The majority of women experience menopause in their early fifties, but biological infertility sets in about 10 to 12 years before menopause. The decline in fertility becomes more pronounced in the early thirties, with a more rapid decrease occurring a few years later, around the age of 37. Several factors contribute to this decline, including a reduction in ovarian reserve, diminished oocyte quality, lower embryo implantation rates, and changes in the hormonal environment leading to ovulatory dysfunction and uterine issues. Additionally, older women have a higher susceptibility to developing conditions such as endometriosis, fibroids, and pelvic infections.
Averages for the percentage of assisted reproductive technology (ART) cycles that result in live births are 31% in women under 35, 24% in 35–37-year-olds, 16% of women 38–40, 8% among women 41–44, and 3% of 43+ women with their own eggs. The optimal age for IVF for women using their own eggs is less than 35 years. After this age limit, the success rate of IVF treatment falls steeply.
The risk of chromosome problems increases with a woman’s age. The chance of having a child with Down syndrome increases over time. The risk is about 1 in 1,250 for a woman who conceives at age 25 and increases to about 1 in 100 for women who conceive at age 40.
If there is a family history of early menopause, women will have a higher risk of premature ovarian failure, leading to an early decline of ovarian reserve and a lower chance of getting very few oocytes and of poorer quality for IVF cycles even at a younger age. They should start fertility testing and treatment earlier.
Elderly women and patients with premature ovarian failure can have successful IVF treatment with donor eggs from a young donor.
For IVF, the highest age restriction for women is 50 years, while the upper age limit for men is 55 years in India, according to the ART law of 2022.
Male Age
Semen parameters also decline with age, but they have a greater effect on quality. As age increases, the morphology of sperm and the DNA inside the sperm get affected, leading to poor-quality embryos, which leads to early miscarriages or IVF failure. Sedentary lifestyles, smoking, alcoholism, and stress factors may lead to poor-quality sperm. But even if the numbers of sperm with normal morphology are lower in the semen of elderly males, we can get a few good sperm and do IVF with a fair chance of pregnancy.
Preconditions For IVF
Women should be devoid of any co-morbidities for the best results with IVF treatment. Uncontrolled Diabetes mellitus can decrease the quality of eggs and cause early miscarriages. Uncontrolled Thyroid disease also affects the outcome of IVF at every level. Obesity or being underweight also affects success, so weight should be in a healthy range. If the uterus has fibroids, adenomyosis, a septum, etc., then the chance of implantation and pregnancy is decreased. With Endometriosis, egg quality becomes poorer, and ongoing pregnancy becomes difficult. General body condition should be good to carry a pregnancy until 9 months. If a woman has diseased fallopian tubes (e.g., hydrosalpinx, history of previous ectopic pregnancy, salpingectomy, etc.), then also embryo implantation can get hampered.
Men should adopt good lifestyle-related habits like quitting smoking, abstaining from alcohol, excessive coffee, or any other recreational drug intake. Co-morbidities should be taken care of with proper and regular medications and frequent follow-ups to check for good control.
Oocyte/Embryo Cryopreservation
If a woman wants to delay or postpone pregnancy due to delayed marriage, carrier constraints, or medical conditions, they may opt for oocyte or embryo cryopreservation through IVF treatment. When we cryopreserve oocytes or embryos, the ageing process in the cell is arrested. So a woman’s age at the time of oocyte cryopreservation is the crucial parameter for future pregnancy with preserved oocytes or embryos.
The author is Professor and HOD, Dept. Reproductive Medicine and Surgery, Amrita Hospital, Kochi.
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