I. Fertility Reduction
The goal of infertility treatment is not only to obtain a pregnancy, but more importantly, to obtain a safe pregnancy and a healthy newborn. Therefore, once a multifetal pregnancy has occurred, decompression can be a remedial measure that is particularly important for multiple pregnancies.
Reduction of multiple pregnancies is an artificial method of reducing one or more embryos in order to improve the outcome of multiple pregnancies, thereby improving the obstetric and other outcomes of the pregnancy. The main types of reduction currently available include transabdominal reduction and transvaginal reduction. What is the clinical choice? The decision needs to be made based on the patient’s condition and gestational week. Reduction is possible from 7 weeks of gestation to late gestation, but is safer in early gestation. If the fetus is larger than 9 weeks, the failure rate of vaginal reduction is high, and transabdominal reduction is needed.
The following principles are mostly referred to for fetal reduction.
1.Select the gestational sac that is favorable for operation, such as the gestational sac closest to the vaginal wall and abdominal wall;
2. Prioritize the extinction of two embryos from a single gestational sac twin (monozygotic twins), while retaining a single gestational sac singleton;
3. Select the gestational sac containing the smallest embryo;
4. Select the gestational sac close to the cervix. For pregnant mothers with acute infections of various organ systems, especially the genitourinary system, and those with preterm miscarriage, they need to wait until the inflammation is controlled or the bleeding symptoms are relieved before decreasing the pregnancy at a later stage.
Every mother-to-be is very concerned about the risk of miscarriage associated with reduction of pregnancy, but in fact this percentage is not very high. A large body of literature shows that the miscarriage rate after reduction is 5.4% at 9-12 weeks of pregnancy, 8.7% at 13-18 weeks of pregnancy, 6.8% at 19-24 weeks of pregnancy, and 9.1% at >25 weeks of pregnancy. These values are much lower than the rate of miscarriage in multiple pregnancies, and we take various measures to minimize the risk of miscarriage, such as performing the procedure under aseptic conditions and using appropriate anti-infective and fetal preservation medications before and after the procedure.
Reduction of multiple pregnancies is now generally considered to be a safe and less invasive and effective method to improve the outcome of multiple pregnancies, as it can prolong the gestational weeks and reduce preterm delivery, as well as reduce the complications of multiple pregnancies.
II. Single blastocyst transfer
A blastocyst is an embryo that has developed to day 5 and is preferentially selected from a day 3 embryo in further culture. The clinical pregnancy rate of blastocyst transfer is higher than that of day 3 embryos, and the success rate in our center can reach over 70%. Nowadays, single blastocyst transfer has been used as a routine technique in multiple fertility centers internationally. More and more countries are now aware of the dangers of multiple and twin births in assisted reproduction, and the resulting problems require more investment.
With the continuous in-depth research on assisted reproduction technology and reproductive basic knowledge, single embryo transfer will become the trend of embryo transfer and will gradually be accepted by more and more patients and reproductive centers to ensure successful pregnancy while minimizing the occurrence of multiple births so that patients can get practical benefits.
III. Precautions and monitoring during pregnancy
1. Pregnancy Monitoring and Obstetrics
In view of the serious maternal and infant complications of multiple pregnancies, prevention of preterm delivery, prolongation of gestational weeks, and reduction of low-body mass births are among the goals of management of multiple pregnancies. Strengthening prenatal education, raising the awareness of self-care and timely consultation of the population, early diagnosis and early treatment of twin pregnancy-related complications, close fetal monitoring, especially for monochorionic twins, and timely intervention and treatment of twin pregnancy transfusion syndrome are helpful to reduce the occurrence of complications and adverse pregnancy outcomes in patients.
For example, ultrasound should be performed in early pregnancy to understand whether the multiple pregnancy is “mono” or “dizygotic”; Down’s syndrome screening should be performed at 11-13+6 weeks of pregnancy, and prenatal diagnosis should be performed if necessary to deal with abnormal fetuses in a timely manner; after 14 weeks of pregnancy, regular ultrasound monitoring (2-3 weeks) is optional. After 14 weeks of gestation, regular ultrasound monitoring (2-3 weeks) can be chosen to observe the size of the twin fetuses, the amount of amniotic fluid and whether it is equal, the fetal growth and structure, etc. for early diagnosis of twin fetus transfusion syndrome, intrauterine growth restriction and fetal malformation;
Ultrasound prenatal diagnosis was performed from 18 to 26 weeks, and after 20 weeks of gestation, uterine height and abdominal circumference were measured weekly and umbilical artery flow index was measured every 3 weeks; at 24 weeks of gestation, cervical length and fetal fibrin were measured to predict preterm labor; after 36 weeks of gestation, weekly obstetric examinations were performed. To prevent the occurrence of hypertensive disorders in pregnancy, basal blood pressure should be measured at an early stage, and blood pressure should be measured regularly to achieve early detection and early intervention.
Some studies have concluded that limiting physical activity and bed rest during pregnancy in expectant mothers with multiple pregnancies can effectively promote fetal growth and improve perinatal outcomes. Therefore, pregnant women with twin pregnancies should have regular maternity checkups and establish individualized prenatal checkup plans for early detection and management of various complications, so as to ultimately achieve longer gestational weeks, reduce the incidence and severity of complications, and improve maternal and infant outcomes.
2. Precautions for pregnant mothers with assisted reproduction for pregnancy
There are still some differences between multiple pregnancies after assisted reproductive technology (ART) and natural multiple pregnancies. Studies have shown that twin pregnancies after ART are prone to premature rupture of membranes leading to mid- and late-term miscarriage, and that acquired cervical insufficiency due to various causes during infertility treatment cannot be ignored. Therefore, in addition to the above-mentioned precautions, mothers-to-be of IVF twin pregnancies should closely monitor the length of the cervix and perform cervical cerclage if necessary.