Monoamniotic Twins
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Information for Women Bogulkunta, Hyderabad - 500 001 Ph : 040 - 40222300 Fax : 040 - 24753482 Email : [email protected] Web : www.fernandezhospital.com What is a Multiple Pregnancy? A multiple pregnancy is a pregnancy with two or more babies. The different terms used depend on the number of babies: Two : Twin Three : Triplets Four : Quadruplets Five : Quintuplets Six : Sextuplets Seven : Septuplets Multiples account for only a small percentage (3%) of all births, but the multiple pregnancy rate is rising. Why are Multiple Pregnancies Increasing? The reason why a woman has a multiple pregnancy may be due to many factors. A few important ones are : Hereditary : A family history increases the chance of having a multiple pregnancy. Maternal Age : About one-third of the increase in multiple pregnancies is due to the fact that more women over age 30 are having babies. Women in this age group are more likely than younger women to conceive multiples. Assisted Reproduction : Medicines that stimulate ovulation help produce many eggs, which if fertilized can result in a multiple pregnancy. In-vitro fertilization, during which eggs are removed from the mother, fertilized in the lab and then transferred to the uterus, result in the transfer of many fertilized eggs into the uterus, thus resulting in a multiple pregnancy. 2 Types of Twin Pregnancy There are two kinds of twins. Non-identical (dizygotic) : Eighty percent of all twins are non-identical. That means they come from two eggs with two sperms fertilizing them. These twins are as similar as siblings can be, of the same or different sex. They have their own placenta (dichorionic) and pregnancy sacs (diamniotic) and are called Dichorionic Diamniotic (DCDA ) twins. The majority of twins from IVF are from two embryos and are non-identical. Identical (Monozygotic) : Twenty percent of twins are identical where one egg is fertilized and then divides into two embryos. These twins are of the same sex, are genetically identical and look alike, but most importantly they share the same placenta (monochorinoic), have separate sacs (diamniotic) and are called Monochorionic Diamniotic (MCDA) twins. Very rarely about 1% of twins may be in the same sac. This is referred to as a Monochorionic Monoamniotic (MoMo) twin pregnancy and carries the highest risk of pregnancy loss. Dichorionic Monochorionic Monochorionic Diamniotic Diamniotic Monoamniotic Why is Multiple Pregnancy a Concern? Most people think of a pregnancy as a happy occasion and consider it a miracle of life. But if one is expecting twins or triplets, one’s joy is 3 often accompanied by a certain amount of anxiety. Mothers carrying multiple pregnancy have a higher chance of developing complications when compared with those mothers with a single baby. Nausea and Vomiting : This can be excessive due to higher levels of pregnancy hormones (Hcg). Other complications include higher chances of miscarriage, which can happen in the first 12 weeks. Vanishing Twin : Sometimes only one baby is lost during the first trimester of pregnancy, but this does not affect the development of the remaining baby. The twin gets completely reabsorbed by the mother (vanishing twin) with no symptoms, and the pregnancy continues. Anemia : This is twice as common in twins than in singletons. Preeclampsia : Preeclampsia, Pregnancy Induced Hypertension (PIH) and high blood pressure are all synonymous terms. Twin pregnancies are twice as likely to be complicated by preeclampsia as single pregnancies. Half of triplet pregnancies develop preeclampsia. Frequent prenatal care increases the chance of detecting and treating preeclampsia. Adequate prenatal care also decreases the chance of a serious problem resulting from preeclampsia for both the babies and mother. Intrauterine Growth Restriction (IUGR) : About half of twins and almost all higher order multiples are born with low birthweights, less than 2,500 gms. This could be due to pre-term birth or poor fetal growth. Multiple gestations grow at approximately the same rate as a single pregnancy up to a certain point. The growth rate of twin pregnancies begins to 4 slow at 30 to 32 weeks. Triplet pregnancies begin slowing at 27 to 28 weeks, while quadruplet pregnancies begin slowing at 25 to 26 weeks. IUGR seems to occur because the placenta cannot any more growth and because the babies are competing for nutrients. The growth of the babies will be monitored with serial growth scans. Gestational Diabetes: This is more common in these women since most of them are in the older age group. The increased risk for gestational diabetes in a multiple pregnany appears to be a result of the two placentas increasing the resistance to insulin, increased placental size, and an elevation in placental hormones. Pre-term Labour : Labour before 37 weeks of pregnancy is called pre-term. More than 50% of twins, 90% of triplets and all quadruplets are born pre-term. The length of pregnancy decreases with each additional baby. On an average, the mean age for delivery is 35 weeks for twins; 32 weeks for triplets; and 29 weeks for quadruplets. Post-Partum Haemorrhage : This could occur because of an overdistended uterus and a large placenta. Management of Multiple Pregnancy We recommend the following : More Frequent Antenatal Visits should be made to check for complications and for monitoring. Nutritional Needs have to be addressed, since more calories are needed to nourish the growing babies and to also meet the mother’s energy needs. 5 More Frequent Fetal Assessment by ultrasound as well as electronic fetal heart monitoring, especially if the twins are monochorionic, small or discordant in growth. Frequent Assessment of Cervix : Ultrasound / clinical assessments of the cervix may be done at regular intervals for measuring the length, since a short cervical length is found to be associated with a higher chance of premature delivery. Cervical Cerclage : A procedure used to suture the cervical opening is done only if the cervix is very short or open, but it is not routinely done in all patients with multiple pregnancy. Restricted Physical Activity : Depending upon complications, one may be advised rest, but staying in bed is not advisable. If a patient goes into pre-term labour, drugs used to stop uterine contractions (Tocolytics) may be advised very judiciously so that delivery can be postponed for a few days at least. Need for Neonatal Care : Since a majority of these babies are either low-birth weight or premature, they need the highest level of neonatal care. How are Multiple Babies Delivered ? Delivery depends on many factors including fetal positions, gestational age and health of the mother and babies. If both the babies are in head down positions and there are no other complications, a vaginal delivery is possible. Caesarean delivery is for babies who are in abnormal positions, or who are discordant in growth, in higher order multiples like triplets and more. Vaginal delivery may take place in the operating room because of 6 a greater risk of complications, which may require a Caesarean Section. What is Multi-Fetal Pregnancy Reduction ? In recent years, a procedure called multi-fetal pregnancy reduction has been used for very high numbers of fetuses, especially four or more. This procedure involves injecting one or more fetuses with medications, causing fetal death. The objective of multi-fetal reduction is to give the remaining fetuses a better chance for survival and health. A Multifetal Pregnancy Reduction (MFPR) : • decreases miscarriage • helps carrying your pregnancy longer • decreases neonatal deaths • improves chances of delivering one or more healthy babies Risks The risks of multifetal pregnancy reduction include miscarriage and premature birth of pregnancies with four or five fetuses. About 5% miscarry after being reduced to twins. The risk of a premature birth is lower in the case of a multifetal reduction than it is for a triplet or more pregnancy. 7 Monochorionic Diamniotic Twins What are Monochorionic Twins? These are twins who come from the same egg, which splits into two and develop into two babies. They share the same placenta are identical and are of the same sex. Why are We Worried? In the majority of women, these pregnancies progress normally, but there is a higher risk of problems than with a single pregnancy or with a twin pregnancy where each baby has its own placenta. The complications which can occur are : Fetal Growth Restriction Because the babies share the same placenta, there are connections between the babies’ blood circulation systems. The blood vessels run backwards and forwards between the two halves of the twins’ shared placenta and each baby receives the same amount of blood from the mother. However, while in some Monochoronic pregnancies the placenta is divided equally between the twins, in approximately 40% of cases one baby has a disproportionately smaller share of placenta. This may result in that baby not growing as well. This is known as fetal growth restriction. In most pregnancies complicated in this way, one twin is small and the other grows normally. This is known as discordant growth. However, in some pregnancies both twins can be small. Twin-to-Twin Transfusion Syndrome (TTTS) What is Twin-to-Twin Transfusion Syndrome (TTTS) ? About 20 percent of identical twins who share a single placenta, 8 develop a complication which is called Twin-to-Twin Transfusion Syndrome. In TTTS, there are abnormal connecting vessels in the placenta that shunt the blood from one twin (the donor) to the other twin (the recipient). As a result, the donor twin receives very little blood from the shared placenta and the recipient twin may have more blood flow, causing it to grow bigger at the expense of the smaller twin. This also causes the larger twin to produce more urine, which is responsible for an increased amount of fluid around the baby (polyhydramnios).