Assisted hatching. About five to six days after fertilization, an embryo "hatches" from its surrounding membrane (zona pellucida), allowing it to implant into the lining of the uterus. If you're an older woman, or if you have had multiple failed IVF attempts, your doctor might recommend assisted hatching — a technique in which a hole is made in the zona pellucida just before transfer to help the embryo hatch and implant. Assisted hatching is also useful for eggs or embryos that have been previously frozen as the process can harden the zona pellucida.
Statistically, the biggest decline in live births happens between the ages of 40 and 42+. In other words, a woman who has just turned 40 has a much higher chance of conceiving and delivering a baby than a woman who has just turned 42. Of course, these numbers and trends concern women using their own eggs. With donor eggs, consider the age of the woman at the time the eggs were harvested and use that age.
Fertility has long been considered a “woman’s problem.” This is simply not true, and men are in fact, equally as infertile as women. Traditionally the metrics for male fertility have been mostly limited to sperm count, morphology, motility, and, occasionally, DNA fragmentation. For females, on the other hand, a vast array of tests are available. These include ultrasound, cervical position, basal body temperature, hysteroscopy, laparoscopy, cycle tracking and a diversity of hormonal tests.
Fertility expert Zita West has noticed this increase at her London clinic. "The main reason," she explains, "is age. Women are having babies later." Exhaustion also plays a part. "The sleeplessness of life with a small child can't be underestimated," she says. "You might still be breastfeeding, you might be sharing a bed with a toddler, you might be holding down a job at the same time. Basically, there's not a lot of sex happening."
^ Hozyasz, K (March 2001). "Coeliac disease and problems associated with reproduction". Ginekol Pol. 72 (3): 173–9. PMID 11398587. Coeliac men may have reversible infertility, and as in women, if gastrointestinal symptoms are mild or absent the diagnosis may be missed. It is important to make diagnosis because the giving of gluten free diet may result in conception and favourable outcome of pregnancy.
Low weight: Obesity is not the only way in which weight can impact fertility. Men who are underweight tend to have lower sperm concentrations than those who are at a normal BMI. For women, being underweight and having extremely low amounts of body fat are associated with ovarian dysfunction and infertility and they have a higher risk for preterm birth. Eating disorders such as anorexia nervosa are also associated with extremely low BMI. Although relatively uncommon, eating disorders can negatively affect menstruation, fertility, and maternal and fetal well-being.
This chart is US national average data on success rates per IVF cycle by female age for 2014. The dark blue line (triangles) shows pregnancy rates per cycle by age. The orange line (circles) shows live birth rates per cycle by age. The rate of singleton live births per cycle is shown by the light blue line. The difference between "pregnancy" rate and "live birth" rate is due to miscarriages.
Problems with the uterus: There are many conditions related to the uterus that can cause secondary infertility. Scarring can occur during a dilation and curettage (D&C) or Cesarean delivery that can create adhesions inside the uterus that interfere with future pregnancies Fibroids or polyps are benign (non-cancer) growths inside the uterus that can impair pregnancy. A retained placenta can cause infection and uterine scarring.
Sometimes problems getting pregnant for a second or subsequent time are related to a complication that occurred in a prior pregnancy or prior to delivery (damage to the uterus, for instance). But most often, secondary infertility is caused by the same factors that would cause primary infertility — issues like advanced age, obesity, ovulation problems and so on.