multiple pregnancies

Multiple Pregnancies

DEFINITION :

• Any pregnancy which two or more embryos or fetuses present in the uterus at same time.

• It is consider as a complication of pregnancy due to ;

The mean gestational age of delivery of twins is approximately 36w.

The perinatal mortality &morbidity increase.

Terminology vs. number

• Singletons one fetus

• Twins tow fetuses.

• Triplets three fetuses.

• Quadruplets four fetuses.

• Quintuplets five fetuses.

• sextuplets six fetuses.

• Septuplets seven fetuses.

Incidence & epidemiology

• The incidence of multiple pregnancy in US is approximately 3% (increase annually due to Assisted Reproductive Technology ART ).

• Monozygotic twins ( approx. 4 in 1000 births ). • Triplet pregnancies ( approx. 1 in 8000 births ). • Multiple gestation increase morbidity & mortality for

both the mother & the fetuses.• Hellin's Law: is the principle that one in about 89

natural pregnancies ends in the birth of twins, triplets once in 892 births, and quadruplets once in 893 births.

Overview

Definitions:

• ZYGOSITY: - Refers to the Type of Conception.-only determined by DNA testing.

• CHORIONICITY: - Type of Placentation/ Sharing the placenta.- prenatally by ultrasound.- postnatally by examining membranes.

A- Dizygotic twins

•Most common represents 2/3 of cases.

•Fertilization of more than one egg by more than one sperm

•Non identical ,may be of different sex.

•Two chorion and two amnion.

•Placenta may be separate or fused.

Cont.

• The incidence of dizygotic twins is higher in:

1. Certain families.

2. Race; African American.

3. Increases with maternal age, parity, weight and height.

4. Ovulation Induction.

B- Monzygotic twins

• Constitutes 1/3 of twins

• These twins are multiple gestations resulting from cleavage of a single, fertilized ovum.

• The timing of cleavage determines the placentation of the pregnancy.

• Not affected by heredity.

• Not related to induction of ovulation

B- Monzygotic twins

1. If separation occurs before the differentiation of the trophoblast, two chorions and two amnions (Di-Di) result.

B- Monzygotic twins

• 2. After trophoblast differentiation and before amnion formation (days 3 to 8), separation leads to a single placenta, one chorion, and two amnions (Mo-Di).

Blastocyct

B- Monzygotic twins

3.Division after amnion formation leads to a single placenta, one chorion, and one amnion (Mo-Mo) (days8 to 13).

B- Monzygotic twins

• 4. Rarely, conjoined or “Siamese” twins (days 13to 15).

Conjoined twins

Which is more important – zygosity or chorionicity??

• Dichorionic twins can be either mono/dizygotic.

• Dichorionic twins develop as two distinct organs. – so no risk.

• Monochorionic twins have increased vascular anastomoses between the two circulation

– so high risk!!

Diagnosis: • History:

-Family hx of dizygotic twins.-Use of fertility drugs.-sensation of excessive fetal movements.-Exaggerated symptoms of pregnancy (hyperemesis gravidarum ).

• Examination: -GPE ( weight gain, Pre-eclampsia signs ).-Abdominal examination (excessive uterine fundal growth, and auscultation of fetal heart rates in separate quadrants of the uterus are suggestive but not diagnostic).

• Sonographic examination ( diagnostic )

Ultrasound differentiation of chorionicity

Ultrasound differentiation of chorionicity

Ultrasound differentiation of zygocity

US

Complications

1. Maternal Complications.

2. Fetal Complications.

1.Maternal Complications

Cont.

2.Fetal Complications

2.Fetal Complications

• Prematurity :

Single most important cause of perinatalmortaility and morbidity.

Ensure delivery in a tertiary care centre.

2.Fetal Complications

• IUGR:Can affect one or both fetuses.

Monochorionic > Dichorionic.

Up to30-32 Weeks twins grow with same velocity , after that reduction in abdominal circumference.

Poor growth – poor placentation , unequal placental sharing, fetal anomalies.

2.Fetal Complications

• Single Fetal Demise

Single Fetal Demise cont.

Monochorionic - 25% risk of twin death, 25% risk of neurological damage in surviving twin.

• Dilemma exists whether to deliver early or not

• Terminated as soon as other twin is capable of extra uterine survival

Dichorionic – no such risk

• Conservative management

2.Fetal Complications

• Twin-Twin Transfusion Syndrome• The presence of unbalanced anastomosis in the placenta

(typically arterial-venous connections) leads to a syndrome in which one twin’s circulation perfuses the other Twin.

• Complications: Donor : anemic HF, hypovolemia, hypotension, anemia,

oligohydramnios, growth restriction. Recipient : hypervolemic HF , hypervolemia, hypertension,

polyhydramnios, thrombosis, hyperviscosity,cardiomegaly, polycythemia, hydrops fetalis.

Twin-Twin Transfusion Syndrome Cont.

Twin-Twin Transfusion Syndrome Cont.

• Management :

Repeated amniocentesis from ( recipient).

Intrauterine transfusion of the anemic (donor) twin is of no benefit in this condition.

Fetoscopy and laser ablation of communicating vessels.

2.Fetal Complications

• Vanishing Twin & Abortion

Incidence of abortion more in multiple pregnancy

Spontaneous cessation of cardiac activity in a previously viable fetus of a multiple gestation. – VANISHING TWIN

When fetal death occur after the first trimester, results in a thin parchment – like body called FETUS PAPYRACEOUS

Diagnosis made after delivery

No effect on mother or the viable fetus.

Vanishing Twin & Abortion

2.Fetal Complications

• Congenital Anomalies

• Unique to twins – conjoined twins , Acardiac fetus

• Non specific but common in twins – CHD , Anencephaly

• Postural deformities – Talipes & Congenital dislocation of Hip

STRUCTURAL MALFORMATIONS

• Dizygotic – independent risk, but both will not be involved

• Monozygotic – same risk as that of singleton, both affected

• Down’s syndrome

CHROMOSOMAL ANOMALIES

Congenital Anomalies Cont.Conjoined Twins

Congenital Anomalies Cont.

• Acardiac Foetus

Very rare

Bizarre form of monochorionic twinning

One fetus is normal

The other twin is severely malformed – no heart , absent development of upper part of body

Acardiac Foetus Cont.

Management • Antepartum : Adequate nutrition.

-Adequacy of maternal diet is assessed due to the increased need for overall calories, iron, vitamins, and folate.-The Institute of Medicine (IOM) recommends women with twins gain a total of 16.0 to 20.5 kg during the pregnancy.

More frequent prenatal visits. Periodic U/S assessment “ every 3-4 weeks from23weeks’

gestation “ to monitor the growth and detection of discordant growth or TTTS.

Amniocentesis .

Management Cont.

• Intrapartum

Delivery should be considered if:1. Fetal lung maturity is demonstrated2. If compromise of the remaining fetus develops.3. If evidence of disseminated intravascular coagulation in the mother is present

Management Cont.

The route of delivery depends on:1. Presentation of the twins.2. Gestational age.3. Presence of maternal or fetal complications.4. Experience of obstetrician.5. Availability of anesthesia & neonatal intensive care.

Management Cont.

• postpartum :

Active management of PPH:

By giving oxytocin in the 3nd stage of labor just after delivery of both fetuses and placentas.