Multiple pregnancy

-The term ‘multiple pregnancy’ is used to describe the development of more than one fetus in utero at the same time. - The rise in treatments for infertility such as IVF and ovulation-stimulating drugs, like clomifene citrate and gonadotrophins.

Twin pregnancy -Types of twin pregnancy Twins will be either monozygotic (MZ) or dizygotic (DZ). Monozygotic or uniovular twins are also referred to as ‘identical twins’. -They develop from the fusion of one oocyte and one spermatozoon, - after fertilization splits into two. - These twins will be of the same sex and have the same genes, blood groups and physical features, such as eye and hair colour, ear shapes and palm creases. -However, they may be of different sizes and often have very different personalities and characters.

Dizygotic or binovular twins: develop from two separate oocytes that are fertilized by two different spermatozoa, - often referred to as ‘non-identical twins’. -They are no more alike than any brother or sister and can be of the same or different sex. -

Because in any pregnancy there is a 50:50 chance of a girl or boy, half of dizygotic twins will be boy-girl pairs. - A quarter of dizygotic twins will be both boys - a quarter both girls. - two-thirds will be dizygotic and one-third monozygotic. - one-third of twins are girls, one-third boys and one-third girl-boy pairs.

Determination of zygosity and chorionicity Midwives must understand the differences between the two terms and why it is important. Dichorionic :Two placenta, Two chorions Monochorionic: One placenta, One chorion -Determination of zygosity means determining whether or not the twins are monozygotic (identical) or dizygotic (non-identical). - By the age of two, parents will know their children so well and see the differences in character and personalities that they find it difficult to believe they can be identical. - At birth, monochorionic twins tend to have a greater weight variation than dichorionic ones.

- monozygotic twins: - a monochorionic diamniotic placenta (MCDA) - the placenta will have two chorions and two amnions (DCDA), • MCMA conjoined twins can develop

Chorionicity: why is it important to know? - monochorionic twin pregnancies have a 3–5 times higher risk of perinatal mortality and morbidity than dichorionic twin pregnancies 1-the chorionicity is determined by ultrasound examination. - The chorions forming the septum between the amniotic sacs can be seen more clearly in the first trimester of pregnancy

If the septum has thickness of 2 If the septum has thickness of 2.4mm or more, a dichorionic twin pregnancy; - if it is a thin septum thickness of 1.4mm, a monochorionic pregnancy -2- studying the septum at its base. -A tongue of placental tissue is seen ultrasonically between the two chorions and this is termed the ‘twin peak’ or ‘lambda sign’

Zygosity determination after birth @-DNA accurate method. -The DNA can be extracted from cells taken from a cheek swab from inside the mouth (buccal cavity ). -@genetic markers 99.99% accurate. - Zygosity determination should be routinely offered to all same-sex twins for the following reasons: •1- Most parents will want to know whether or not their twins are identical,: ‘Are they identical?’; also as the twins get older they usually want to know. • 2- considering further pregnancies, they will want to know the risk of having twins again. -

DZ twins tend to run in families -usually on the female side ,though not in all cases. -MZ twins do not run in families •3- It will help the twins in establishing their sense of identity; -4-it will influence their life and family relationships. •5- The information is important for genetic reasons, not just with monogenic disorders but with any serious illness later in life. • 6-Twins are frequently asked to be involved in research where knowledge of zygosity is essential

Diagnosis of twin pregnancy -ultrasound examination. - 6 weeks -20th and 22nd weeks. -When booking a woman in the antenatal clinic a family history of twins should alert the midwife to the possibility of a multiple pregnancy. - If the pregnancy is diagnosed at 6 weeks, the woman should be told about ‘vanishing twin syndrome -Occasionally one fetus may die in the second trimester and become a fetus papyraceous,which then becomes embedded in the placenta and expelled with the placenta at delivery. -This is very rare

Abdominal examination Inspection -On inspection, the size of the uterus may be larger than expected for the period of gestation, particularly after the 20th week. -The uterus may look broad or round and fetal movements may be seen over a wide area, -although the findings are not diagnostic of twins. - Fresh striae gravidarum may be apparent.

- the amount of amniotic fluid is normal in a twin pregnancy but polyhydramnios is common complication of a twin pregnancy, particularly with monochorionic twins. Palpation - the fundal height may be greater than expected for the period of gestation. - The presence of two fetal poles (head or breech) in the fundus of the uterus may be revealed on palpation and multiple fetal limbs may also be palpable.

- The head may be small in relation to the size of the uterus and may suggest that the fetus is also small and that there may therefore be more than one present. -Lateral palpation may reveal two fetal backs or limbs on both sides.

Auscultation -Hearing two fetal hearts is not diagnostic as one can often be heard over a wide area in a singleton pregnancy. -If simultaneous comparison of the heart rates reveals a difference of at least 10 b.p.m., it may be assumed that two hearts are being heard.

The pregnancy A multiple pregnancy tends to be shorter than a single pregnancy. The average gestation for twins is 37 weeks, for triplets 34 weeks and for quadruplets, 33 weeks .

Effects of pregnancy Exacerbation of common disorders - Sickness, nausea and heartburn may be more persistent and more trouble. Anaemia -Iron deficiency - folic acid deficiency anemia are common in twin pregnancies. -Routine oral iron supplementation remains a controversial issue Polyhydramnios -common with monochorionic twins and with fetal abnormalities. -add discoamfort to woman -If acute polyhydramnios occurs, it can lead to miscarriage or premature labor.

Pressure symptoms -The increased weight and size of the uterus . -Impaired venous return from the lower limbs increases the tendency to varicose veins and edema of the legs. - Backache is common - increased uterine size may also lead to marked dyspnoea and indigestion.

Antenatal screening The recommended method of screening is by measurement of the nuchal translucency, - biochemistry • Nuchal translucency for Down syndrome is accurate between 11 and 13 weeks • Chorionic villi sampling (CVS) is not usually recommended in multiple pregnancy as loss rates are high. • Amniocentesis can be performed in twin pregnancies

between 15 and 20 weeks. It should be performed in a specialist fetal medicine unit. Most obstetricians prefer to do a dual needle insertion so there is no chance of contamination between the two sacs. • Chorionicity should be determined in the first trimester.

All monozygotic twins should have echocardiography performed at approximately 24 weeks' gestation, - higher risk of cardiac anomalies in these babies.

Ultrasound examination Monochorionic twin pregnancies should be scanned every 2 weeks from diagnosis to check for discordant fetal growth and signs of twin-to-twin transfusion syndrome (TTTS). -A cardiac anomaly scan should be performed at 24 weeks. • Dichorionic twin pregnancies should be scanned at 20 weeks for anomalies, , and then usually every 4 weeks.

Antenatal preparation Early diagnosis of a twin pregnancy and of chorionicity is extremely important. Parent education -When a multiple pregnancy is diagnosed, written information on multiple pregnancy should be given to the mother.

-This should include contact phone numbers of any local support organizations - the midwife should give them the opportunity to discuss any worries or problems they may have, as two babies will add a considerable financial burden to any family's income

Preparation for breastfeeding -focus on nutritional need of the mother - Mothers should be encouraged that it is possible to breastfeed two, and in some cases three babies. -Early in the antenatal period the mother should be given as much information and advice as possible about both breast- and bottle-feeding, so she can make an informed choice on how to feed her babies

Topics for parent education classes Facts and figures on twins and twinning • Diet and exercise • Parental anxieties about obstetric complications • Labour, pain relief and the birth • Possibilities of premature labour and birth and the outcome • Visit to the neonatal unit •

Breastfeeding and bottle-feeding • Zygosity • Coping with newborn twins or more • Development of twins including individuality and identity • Sources of help. .

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