— How is in vitro fertilization performed in modern clinics today?
In essence, in vitro fertilization mirrors what happens in natural conception inside the body. An egg is retrieved, sperm is introduced, and the most active sperm fertilize the egg on their own. The process is carefully guided in a controlled laboratory environment to optimize the chances of a healthy embryo.
— When is this procedure typically indicated?
The primary indications include blocked fallopian tubes, a high risk of fetal genetic abnormalities, a limited number of eggs retrieved, or significant male-factor infertility where sperm cannot fertilize an egg unaided. In cases of severe male-factor infertility and when other methods have failed, intracytoplasmic sperm injection (ICSI) is often employed as part of the treatment plan.
— How is the ICSI procedure carried out, and how does it differ from conventional IVF?
During ICSI, a single, well-selected sperm is injected directly into the cytoplasm of the egg. This precise technique bypasses many barriers to fertilization and is used when sperm quality or quantity is a concern. Pre-implantation genetic testing (PGT) of embryos is also available within assisted reproductive technologies. Modern imaging and molecular methods allow clinicians to assess the embryo’s chromosomal complement before transfer to the uterus. When maternal age is advanced and paternal age falls within a higher range, this diagnostic approach can help reduce miscarriage risk and the chance of chromosomal disorders such as Down syndrome, Edwards syndrome, and Patau syndrome, among others.
— Is it possible to influence the sex of an embryo in a test tube, for example, selecting an X-bearing sperm to create a girl?
That cannot be done. Determining the chromosome carried by sperm would require destruction of the sperm. In practice, several embryos are created, and genetic testing can reveal the embryo’s sex. However, gender selection has been restricted in Russia since 2012 to prevent sex-skewed births, with certain medical exceptions.
— What are those exceptions?
Embryos with a high likelihood of implantation are prioritized. Exceptions include the avoidance of sex-linked genetic diseases, such as hemophilia, where selecting a female embryo can prevent the disease risk in a male offspring.
— There are rumors that the chance of having a boy or a girl can be influenced by timing or vaginal pH. Do these hold any truth?
There are claims that the sex of the child might be linked to vaginal acidity, with some suggesting methods to favor a boy on certain cycle days. Scientific consensus does not support these methods. Sperm carrying the Y chromosome may prefer a slightly alkaline environment after ovulation, while X-chromosome sperm may thrive in a more acidic milieu, but these ideas lack reliable evidence. Overall, no proven, repeatable method exists to steer the child’s sex through timing or environment.
— Another indication for IVF is secondary infertility. What does that mean?
Secondary infertility occurs when a person has previously conceived but is unable to become pregnant again within a set period. For individuals under 35, this is defined as not achieving a pregnancy within 12 months, and for those 35 and older, within 6 months. Sometimes the reasons remain unclear, and prior fertility does not guarantee future ease of conception.
— Why does fertility decline after age 35 in many patients?
Age accelerates the decline in both the quantity and quality of eggs. As a result, clinicians may diagnose infertility earlier and, if needed, initiate an IVF program sooner, especially when there are signs of reduced ovarian reserve.
— Is there an upper age limit for IVF?
Typically, IVF is considered less likely to result in a pregnancy around the ages of 42 to 43, with natural pregnancy chances diminishing to about 3–4% at that point. In many places, there is no formal age restriction, though clinics may have practical guidelines. When a person lacks viable own eggs, donor egg IVF becomes an option.
— Why is the birth rate lower after age 40?
With advancing age, IVF carries a higher risk of pregnancy complications and adverse birth outcomes, including cesarean delivery, gestational diabetes, preeclampsia, prematurity, and fetal growth restriction. These risks are linked to age-related changes, comorbidities, and blood-thinning tendencies that accompany aging. Twin pregnancies after age 40 carry additional risks for both the mother and babies.
— What specific complications are associated with multiple pregnancies?
Twins dramatically raise the risk of preterm birth, low birth weight, cerebral palsy, and autism that can arise from fetal hypoxia. Modern research continues to explore these associations, underscoring the preference for single-embryo transfers when clinically appropriate to minimize risk.
— Which lifestyle factors influence IVF outcomes beyond age?
Egg quality can be affected by smoking, obesity, chronic illnesses, hormonal imbalances, and certain vitamin deficiencies. Yet age remains the most influential factor. Even natural conception rates decline notably after 30 compared with younger ages.
— Can egg quality be improved through lifestyle changes?
Some studies point to melatonin as having a potential positive effect on egg and embryo quality. Maintaining a regular sleep schedule, ensuring 7–8 hours of sleep, and adopting an early sleep-wake pattern may support melatonin production. Folate and vitamin D supplementation alongside a balanced diet may also help. These measures should be discussed with a clinician as part of a broader plan for reproductive health.
— Does smoking affect IVF success, and does nicotine-free vaping pose the same risks?
There is no definitive, comprehensive study comparing nicotine-containing and nicotine-free e-cigarettes in relation to IVF. Vaping devices can release substances like PM2.5 particles and bisphenols from plastics, which may negatively impact egg function. More research is needed, and the current data on electronic devices, microwaves, and mobile phones remains limited.
— What about vitamin D and egg quality? Is there scientific backing?
Numerous studies suggest adequate vitamin D levels correlate with better reproductive outcomes and may influence the effectiveness of assisted reproductive technologies. Seasonal variations in anti-Mfcllerian hormone (AMH) and ovarian response have been noted, with some findings indicating vitamin D could help stabilize these fluctuations. While the evidence is not uniformly conclusive, clinicians often monitor vitamin D and aim for balanced levels to support fertility efforts.
— How do high doses of vitamin D affect the body?
Excessive vitamin D can disrupt calcium balance and potentially lead to hypercalcemia, with fatigue, nausea, and mood changes among possible symptoms. Hypercalcemia can also impact reproductive health, so dosing should be guided by medical advice and blood tests.
— Is regular physical activity beneficial for reproductive health?
Exercise supports a healthy weight and promotes adequate blood flow to the ovaries and uterus. However, extreme training, especially at professional levels, can reduce fat stores and trigger a set of concerns known as the female athlete triad, which includes irregular periods and bone density loss.
— What is the female athlete triad, and how does it relate to fertility?
The triad comprises reduced body fat, menstrual irregularities, and low bone mass. It can lead to low estrogen and compromised reproductive health. In some cases, clinicians may prescribe hormone replacements to help patients regain balance while continuing to stay active in a balanced way. For most women, moderate exercise and maintaining a healthy weight remain advisable to minimize obstetric complications such as preeclampsia, anemia, labor difficulties, miscarriage, and risks associated with high or low birth weight babies.