Women undergoing the fertility treatment, ICSI, are much more likely to suffer a miscarriage in the first trimester if they are over the age of 37, new research has shown.
ICSI (intracytoplasmic sperm injection) is very similar to IVF (in vitro fertilisation) in that eggs and sperm are collected from each partner. The difference between the two procedures is the method of achieving fertilisation.
With conventional IVF, the eggs and sperm are mixed together in a dish and the sperm fertilises the egg ‘naturally'. With ICSI, a single sperm is injected directly into each egg. As very few sperm are required, this method is often used when there is an issue with the sperm, such as a low sperm count or poor motility (movement).
Belgian researchers analysed data on 23,354 cycles of ICSI, which were carried out over an 18-year period, from 1992 to 2009.
The researchers found that the live birth rate was highly dependent on ovarian response. Women who had 11 or more eggs retrieved after stimulation had the best chance of a successful pregnancy. Women who had six to 10 eggs retrieved had a 4.3% lower chance of a live birth than those with 11 or more, while those with one to five eggs had a 16.4% lower chance.
The study also found that the chances of a preclinical abortion (defined as a miscarriage so early in the pregnancy that there is no clinical or ultrasound evidence of the pregnancy), miscarriage and overall pregnancy loss during the first trimester remained constant until the age of 34, but increased steadily from the age of 35 onwards. Women were significantly more likely to miscarry if they were over the age of 37.
On average, rates of preclinical abortion, miscarriage and overall pregnancy loss in the first trimester were 8.5%, 6.8% and 16.9% respectively until the age of 37. Between the ages of 38-40 the rates rose to 13.8%, 16.6% and 33.8% respectively, and between the ages of 41-43 the rates rose to 21.6%, 31.6% and 56.7% respectively.
The study did however find that the risk of an ectopic pregnancy was not related to the age of the patient and remained at an average of 1.9% per cycle - a rate that is approximately the same as that seen in the general population. The researchers said that this would be ‘reassuring news for women undergoing fertility treatment'.
"This analysis provides interesting information regarding the outcome for patients undergoing an ICSI treatment. It demonstrates the strong correlation between ovarian response and the chances of achieving a live birth after ICSI. It enables the fertility specialists as well as the patients to calculate the chances of a pre-clinical abortion, a miscarriage or a live birth.
"The study also shows a strong increase in first trimester pregnancy loss after the age of 38, with an even more pronounced increase after the age of 40. These findings illustrate the important risks associated with the delay of childbirth to more advanced ages, especially until after the age of 38," the researchers from the Centre for Reproductive Medicine in Brussels said.
Details of these findings were presented at the annual conference of the European Society of Human Reproduction and Embryology in Stockholm. Read More
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