Having twins as a results of in vitro fertilization (IVF) carries higher risks of complications for both mother and babies than having two single babies from separate IVF procedures, according to a Swedish study.
The extra concerns that come with multiple births are nothing new. Btu even as many fertility clinics have stopped regularly transferring more than one embryo, debate has continued over whether having twins through IVF is really a bad thing for couples desperate for children.
“The neonatal and maternal outcomes were dramatically better for women undergoing two IVF singleton pregnancies compared with one IVF twin pregnancy after double-embryo transfer,” wrote lead researcher Antonina Sazonova in the journal Fertility and Sterility.
“These results support single-embryo transfer to minimize the risks associated with twin pregnancies,” added Sazonova of Sahlgrenska University Hospital in Gothenburg, Sweden.
The researchers analyzed data from fresh and frozen embryo transfers done at Swedish IVF clinics between 2002 and 2006. Those records included 991 women who ultimately gave birth to twins after a double embryo transfer and 921 mothers with two children born through separate rounds of IVF.
Almost 47 percent of twin babies were born prematurely and 39 percent were considered low birth weight, the team reported. That compared to the seven percent of singleton babies that were preemies and less than five percent born small.
Twins were also more likely to have breathing complications, sepsis or jaundice. Their mothers had two to three times more preeclampsia - high blood pressure and protein in the urine - and were four times more likely to need a C-section than women who had two single births.
What is involved with in vitro fertilization?
There are five basic steps in the IVF and embryo transfer process which include the following:
Monitor and stimulate the development of healthy egg(s) in the ovaries.
Collect the eggs.
Secure the sperm.
Combine the eggs and sperm together in the laboratory and provide the appropriate environment for fertilization and early embryo growth.
Transfer embryos into the uterus.
Step 1: Fertility medications are prescribed to control the timing of the egg ripening and to increase the chance of collecting multiple eggs during one of the woman’s cycles. This is often referred to as ovulation induction. Multiple eggs are desired because some eggs will not develop or fertilize after retrieval. Egg development is monitored using ultrasound to examine the ovaries, and urine or blood test samples are taken to check hormone levels.
Step 2: Eggs are retrieved through a minor surgical procedure that uses ultrasound imaging to guide a hollow needle through the pelvic cavity. Sedation and local anesthesia are provided to reduce and remove potential discomfort. The eggs are removed from the ovaries using a hollow needle, a procedure called follicular aspiration. Some women may experience cramping on the day of retrieval, which usually subsides the following day; however, a feeling of fullness or pressure may continue for several weeks following the procedure.
Step 3: Sperm, usually obtained by ejaculation is prepared for combining with the eggs.
Step 4: In a process called insemination, the sperm and eggs are placed in incubators located in the laboratory. The incubators enable fertilization to occur. In some cases where there is a lower probability of fertilization, intracytoplasmic sperm injection (ICSI) may be used. Through this procedure, a single sperm is injected directly into the egg in an attempt to achieve fertilization. The eggs are monitored to confirm that fertilization and cell division are taking place. Once this occurs, the fertilized eggs are considered embryos.
Step 5: The embryos are usually transferred into the woman’s uterus from one to six days later, but in most cases the transfer occurs between two to three days following egg retrieval. At this stage, the fertilized egg has developed into a two-to-four cell embryo. The transfer process involves a speculum which is inserted into the vagina to expose the cervix. A predetermined number of embryos are suspended in fluid and gently placed through a catheter into the womb. This process is often guided by ultrasound. The procedure is usually painless, but some women experience mild cramping.
These steps are followed by rest and watching for early pregnancy symptoms. A blood test and potentially an ultrasound will be used to determine if successful implantation and pregnancy have occurred
However, there was no difference in the babies’ chances of having severe malformations and other life-threatening health problems.
“A lot of patients, when they’ve had infertility for a long time, think that it’s a bonus to get two,” said Lynn Westphal, a women’s health and fertility specialist at Stanford University Medical Center in Palo Alto, California.
“We know it’s always safest to have one child at a time,” added Westphal, who wasn’t involved in the new study, adding that she and her colleagues have been counseling more and more women to have a single embryo transferred, especially the younger and healthier patients.