In a nutshell
This study examined the rate of ectopic pregnancy after in vitro ferilization differed with the use of fresh or frozen-thawed eggs.
In-vitro fertilization (IVF) is when a male sperm fertilizes the females’ egg in a laboratory dish outside the body, and is implanted into the woman's uterus (womb). It is commonly used in infertility. IVF can be done in two ways. Fresh embryo transfers (FET) involve the stimulation of the ovaries using hormonal medication to produce an egg. In FET the hormone levels in the uterus at the time of transfer may be higher than normal. Frozen thawed embryo transfer (FTET) involves fertilized eggs that are frozen, thawed and implanted into the uterus during the patient’s natural hormonal cycle. FTET occurs in a uterine environment close to that of normal conception. The process for implanting donor eggs is similar.
An ectopic pregnancy (EP) is a pregnancy that does not implant in the uterus but begins to grow in the fallopian tube. An EP is a medical emergency, as it can have serious health and fertility consequences for the mother and can lead to death.
It is not clear whether ectopic pregnancy is more common during FET or FTET IVF cycles.
Methods & findings
103,070 embryo (fertilized eggs) transfers that resulted in a clinical pregnancy (an early pregnancy visible by ultrasound) were included in this study. These were either intrauterine (implanted in the uterus), ectopic or heterotopic (a simultaneous intrauterine and ectopic pregnancy). 19,486 of these cycles involved a donor egg.
69.8% of all embryo transfers were FET. 30.2% of cycles used FTET.
1.38% of all cycles resulted in an EP. This included 1,356 ectopic and 70 heterotopic pregnancies. EPs were higher when the mothers' own egg was used (1.5%) compared to those involving a donor egg (0.93%).
The chances of an EP were 65% lower in women who underwent a FTET as opposed to a FET with their own eggs. In IVF cycles where donor eggs were used, there was no link between EP and embryo transfer type.
Women who had both a fresh and frozen transfer of their own eggs had a lower risk (88%) of EP in their frozen cycles compared with their fresh cycles.
The bottom line
The study concluded that there is a lower chance of having an EP if frozen fertilized eggs are used in IVF, compared to fresh cycles.
The fine print
The researchers did not have access to information such as the patients’ weight and smoking status, which may have affected the outcomes.
Talk to your physician if you would like to discuss different types of IVF.
Published By :
Fertility and Sterility
May 05, 2015