When there is more than one fetus is in utero, the term plural or multiple pregnancy is applied. Twin pregnancy occurs about 1 in 100 pregnancy.
While triplets occur 1 in every 8000 to 9000 pregnancies.This article shall be lengthy, consider the table of contents:
Table of Contents
What is multiple pregnancy?
Multiple pregnancy is a state of have more than one fetus developing in the uterus simultaneously. There are various forms of multiple pregnancy such as twin, triplet, quadruplet and other high order of multiple gestation. However, twin pregnancy is the commonest form of multifetal pregnancy.
Currently, the incidence of multiple pregnancy has drastically increased globally due to high use of ovulation inducing drugs assisted reproductive techniques. However, naturally, twinning is greater in the black race than in Caucasian.
Multiple pregnancy symptoms
These are not different from those of normal pregancy and may include:
- Missed period
- Nausea and vomiting (morning sickness)
- Breast tenderness and enlargement
- Earlier/raid weight gain
- Intense fatigue or tiredness
- Increased appetite.
Difference Between Singleton Pregnancy and Twin Pregnancy
While pregancy is a special period in every woman’s life, twin pregnancy is different from singleton because of these following effects on pregancy:
- Exacerbation of minor disorders of pregnancy: Nausea and vomiting (morning sickness) and heartburn may be more persist.
- Anaemia: Iron deficiency or folic acid deficiency anaemia are common. Early growth and development of the uterus and its contents make greater demands on maternal iron stores. In later pregnancy (after the 28th week) fetal demands for iron deplete those stores further.
- Pregnancy induced Hypertension: This is more common in twin pregnancy and may be associated with the larger placenta site or the increased hormonal output the incidence tends to be greater in monozygotic twin pregnancies.
- Polyhydramnios: It is common and associated with monozygotic twins and with fetal abnormalities. If acute polyhydramnios occurs it tends to lead to abortion.
- Pressure symptoms: Tendency to oedema of ankle and varicose veins is increased Dyspnoea and indigestion are more marked, including backache during multiple pregnancy.
- Age: an increasing in age brings about increasing incidence of twinning, although, this decline after the age of 35 years.
- Parity: high parity results to twinning pregnancy.
- Race: black race has higher rate of twinning than Caucasians but it is highest among the Yorubas of Southwestern Nigeria.
- Hereditary: twinning runs in the family, especially dizygotic twin in whom a daughter usually inherits from the mother.
- Diet: some recent studies have isolated a clomiphene-like substance in staple food such as yams, sweet potatoes, etc. which enhance the ovarian function.
- Use of contraceptives: There is also increasing incidence of twin pregnancy when conceiving immediately after stopping the intake of combined oral contraceptives (COCs).
- Use of fertility drug such clomiphene: use of this drug and other assisted reproductive techniques such as In-vitro fertilization(I.V.F) or intrauterine insemination(I.U.I) have been found to be associated increasing rate of multiple pregnancy.
- Continued breastfeeding: breastfeeding old baby while having sex enhance the chances of having twins because prolactin produced promotes ovarian function.
- The presence of two fetal poles (head or breech) multiple fetal limbs;
- Lateral palpation may reveal two fetal backs or limbs on both sides;
- Pelvic palpation one fetus may lie behind the other and make palpation difficult.
- Hydatidiform mole: during early pregnancy, it could present similar clinical features as multiple pregnancy. The estimation of beta-subunit of human Chorionic gonadotrophin is abnormally high in molar pregnancy. The ultrasound scan carried out reveals a “snow storm” appearance in the cases of hydatidiform mole.
- Wrong dates: If the woman didn’t know her right date of last menstrual period (LMP), the gestational age would be calculated wrongly leading to false diagnosis of twin gestation. Ultrasound helps to confirm this.
- Macrosomic fetus: Large baby would make the uterus look larger than the expected gestational age.
- Polyhydramnios: The excess amniotic fluid makes the uterus to be larger than the expected gestational age.
- Abdomino-pelvic tumor: e.g. fibroids or ovarian tumours co-exiting with pregnancy.
- Early diagnosis is important in order to provide dietary advice on iron folic acid and vitamins which help to keep her haemoglobin level normal.
- Frequent antenatal check up to detect pregnancy-induced hypertension or any other complications.
- Admission to hospital for relief discomfort in later pregnancy.
- The midwife should manage woman with multiple pregnancy in consultation with the obstetrician.
- Exaggeration of early pregnancy symptoms: Symptoms of early pregnancy tend to be increased more in multiple pregnancies than in singleton pregnancy. Hyperemesis gravidarum is usually common including heartburn.
- Anaemia: pregnant women in developing countries are usually prone to iron and folic acid deficiencies because of poor nutrition, malaria and worm infestation than in developed countries. The increasing demand of these essential nutrients by the growing fetus deteriorates the already existing anaemia.
- Polyhydramnios: The incidence of hydramnios is high in multiple pregnancy than in singleton pregnancy. Hydramnios is common in uniovular or monozygotic twins and fetal abnormality (e.g. oesophageal atresia, twin-twin transfusion syndrome). This condition causes more discomfort due to over-distention of the uterus. When hydramnios occurs acutely, it results in miscarriage or preterm labour.
- Exacerbation of pressure effects: The increasing weight and size of the uterus and its contents cause more trouble to the woman. This can impair venous return from lower extremity resulting in increased incidence of varicose veins, haemorrhoids and oedema of the legs. A woman with multiple gestation experiences more backache, marked dyspnoea and indigestion than woman with singleton pregnancy.
- More morbidity of pregnancy: Twin pregnancy increases the complications of pregnancy such as pelvic girdle pain and cholestasis.
- Pregnancy induced hypertension and pre-eclampsia: These are more common in twin gestation than in singletons.
- Antepartum haemorrhage: encroachment on the lower uterine segment by the large placenta may cause placenta praevia. Also, abruptio placentae can complicate pre-eclampsia which is common in this condition.
- Increased operative delivery: Multiple pregnancy has high tendency of malpresentation than in singletons and this can lead to increased operative delivery such as Caeserean section. Operative delivery can cause maternal and neonatal morbidity.
- Retained placenta: It occurs from uterine atony (over-distention of the uterus by the multifetal gestation) result in poor contractions of the uterus in the third stage of labour.
- Postpartum haemorrhage: This can be caused by uterine atony and bleeding from the wide site of the placental bed associated with twin gestation. In some cases, the encroachment of the lower uterine segment by the big placenta results in poor contractions of the uterus – risk factor for postpartum haemorrhage.
- Prolonged labour: The incidence the prolonged labour is high in twin pregnancy than in singletons. This is due to malpresentation leading to poor uterine action and over-distention of the uterus, which also causes poor uterine activity. Although labour tends to progress normally in most multifetal gestation.
- Prematurity: Average gestational age at which birth in twins is about 37.4 weeks compared to 39.7 in singletons. The incidence of premature labour in twin gestation is about 10%. Moreover, preterm labour is higher in monozygotic twins than in dizygotic twin.
- Miscarriage: In early pregnancy, fetal loss is very common. That is, “Vanishing twin” phenomenon.
- Low birth weight: The occurrence of low birth weight is higher in multiple conception (about 10 times) than in singleton pregnancy. That is, giving birth to twin babies of birth weight less than 2.5kg is common and may be caused by prematurity or intrauterine growth restriction or both.
- Intrauterine growth restriction: This could occur from feto-fetal transfusion syndrome (twin-to-twin transfusion syndrome), pre-eclampsia or insertion of the cord in the membranes (velamentous insertion) leading to disruption of feto-placental functions.
- Twin-to-twin transfusion syndrome (TTS): This is a condition where there is blood transfusing from one fetus (donor) to the other (recipient) via vascular anastomosis in a monochorionic placenta. TTS incidence is higher in monozygotic twins (about 20%) and it may be acute occurring in labour or chronic occurring during pregnancy. Complications of this condition are intrauterine growth restriction, fetal anaemia as seen in donor twin, fetal hydrops as seen in recipient twin and fetal death as a result of cardiac failure.
- Congenital malformation: fetal malformation is higher in monozygotic twins than in dizygotic twins and this is due to incomplete division of the fertilized ovum. Conjoining of fetuses can occur in various sites and degrees of fusion, e.g. thoracopagus (conjoined twins fused at the thorax(about 70% rate of incidence), cephalopagus(conjoined twins united at the head). Conjoined twins birth is by Caeserean section and separation of them is possible via surgery.
- Cord prolapse: Malpresentation, polyhydramnios and poor fitting of the presenting part lead to cord prolapse. However, second twin is particularly at higher risk of cord prolapse.
- Preterm rupture of membranes: Malpresentation due to polyhydramnios can cause preterm rupture of the membranes.
- Fetal endoparasitism (fetus -in-fetus): This occurs when part of a fetus is stucked or lodged within the other. This is more common in monozygotic twins. Depending on the site and extent of union and the degree to which essential organs are damaged, fetal demise can occur.
- Premature expulsion of the placenta: The placenta may be expelled before the birth of second twin especially in monochorionic twins where they shared the same placenta. Whereas in dichorionic twins with separate placentae, one placenta is delivered separately. The premature expelling of the placenta leads to increased risk of severe asphyxia and death of the second twin. Moreover, bleeding is likely to occur if one twin is retained in-utero because of the prevention of adequate retraction of placental site.
- Locked Twins: This is very rare complication which occurs when the presentation of the first twin is breech and that of the second twin is cephalic/vertex or when both are cephalic presentation. In both cases, the head of the second twin hinders the progressive descent of the first twin. This serious complication is more common in primigravidae than in multiparous women.
- Retained second twin: This may not occur where twins are properly managed. It results from poor management of twin gestation in labour and is associated with high perinatal morbidity and mortality especially in unbooked cases..
- Reversed atrial perfusion: This is a rare complication of multifetal gestation occurring about 1 in 30,000 births. In this situation, one has a well-developed cardiac structure while the other twin is without well-developed cardiac structure and is only sustained by placental anastomoses to the circulatory system of well-developed fetus.
- Monoamniotic twins: About 1% of monozygotic (MZ) twins have the same amniotic sac in common. This therefore, increases the risk of cord entanglement with occlusion of the blood perfusion via the umbilical cord to one or both fetuses. Sometimes, amniotic fluid level is reduced by use of Sulindac and elective Caeserean section is done around 32-34 weeks of gestation.
- Delay interval birth of second twin: Sometimes, the first twin may be born prematurely before actual labour starts in few days or weeks’ time leading to the birth of second twin. During this period of delay, antenatal corticosteroid is usually given to the mother to assist in maturation of the lungs of the second twin. Also the mother and s giving close and careful monitoring for the signs of infections and fetal compromise as well as psychotherapy to allay her anxiety as regards the preterm twin who either being demised or in the neonatal intensive care unit.
How to increase the chances of twin pregnancy
The following factors predispose to twinning:
Types of multiple pregnancy
Multiple pregnancy is classified into two which are:
1. Monozygotic (Uniovular)
2. Dizygotic (Binovular)
Monozygotic (Uniovular) Twins
Monozygotic (MZ) or single ovum twins are known as identical twins. Monozygotic twins develop from one ovum which has been fertilized by one spermatozoon, always of same sex; they share one placenta and one chorion. A few have two chorions. There is a connection between the circulations of blood in the two babies. Finger and palm prints are identical. Errors in development are more likely in monozygotic twins and conjoined twins are more common.
Dizygotic (Binovular) Twins
Dizygotic (DZ) or double ova twins develop from the fertilization of two ovum and two spermatozoa and are more common than monozygotic twins.
These twins have two placenta may be fused to form one amniotic sacs, two chorions and no connection between fetal circulations. The babies may or may not be of the same sex and their physical and mental characteristics can be as different as in any members of one family.
Difference between monozygotic and dizygotic twins
|Dizygotic (binovular) twins
|Two placenta(mat be fused)
|One chorion(few have two)
|Different sexes or same sex
Diagnosis of twin pregnancy
Diagnosis of twin pregnancy may be difficult, although a family history of twins should alter the midwife to the possibility.
Inspection: The size of the uterus may be larger than expected for the period of gestation after the 20th week. However, it is not correct diagnosis of twin pregnancy as fetal macrosomia, hydramnios, or pelvic tumours can complicate singleton pregnancy to show up as multifetal gestation.
Palpation: The fundal height may be greater than expected for the period of gestation. There may be:
Auscultation: Hearing two fetal hearts is not diagnostic. Comparison of the heart rates should reveals difference of at least 10 beats per minutes.
Ultrasound: It will demonstrate two heads at 15 weeks when the outline of the head will be noted. X -ray- may be used after the 12th week of gestation.
Differential diagnosis of multiple pregnancy
Management of multiple pregnancy
Labour and Delivery of multiple pregnancy
Effect on labour: Labour occurs spontaneously before term due to over stretching of the uterus or may be induced early if complications arise. Preterm labour, babies light for dates and malpresentation.
Management of twin delivery
1st stage of labour: It should be conducted normally; preparation should be made for the reception of two immature babies. Good nursing care to alleviate minor discomfort is highly encouraged.
If fetal distress occurs during labour, delivery will need to be expedited, often by caesarean section. If the uterine activity is poor the use of intravenous oxytocin may be required. If the pregnancy is preterm neonatal care unit should be informed. Two incubators should be in readiness. The room should be warm.
2nd stage of labour: An obstetrician, anesthetist and paediatrician should be present during this stage of labour because of the risk of complication.
Resuscitation equipment should be prepared. The delivery trolley should include equipment for episiotomy, amniotomy, forceps and extra cord clamp and equipment for delivery.
An elective episiotomy may be considered if there are complication like preterm labour and fetal distress. The second stage is conducted as usual up to the birth of the first baby.
After delivery of the first twin an abdominal examination is made to ascertain the lie, presentation and position of the second fetus and to auscultate the fetal heart. If the lie is not longitudinal, an attempt is made to correct it by external cephalic version.
If the presenting part is not engaged it should be pushed in to the pelvis by fundal pressure before the second sac of membranes is ruptured. Stimulate the contraction with intravenous Syntocinon. When the presenting part became visible the
mother is encouraged to push with contraction to deliver the second twin.
With three or four good contractions and effective pushing the 2nd baby has to be delivered within 15 minutes. The babies are labeled as “Twin one” and “Twin two” and the time of delivery and the sex of the child is recorded.
3rd Stage of Labour: Once an oxytocic drug has taken effect, controlled cord traction is applied to both cords simultaneously and delivery of the placenta should be done without delay. Emptying the uterus enables the control of bleeding and the prevention of post-partum haemorrhage.
The placenta should be examined for completeness and to detect deviation from the normal. The umbilical cords should be examined for the number of cord vessels.
Management of Puerperium in multiple pregnancy
General care is the same as the care given in single delivery. Involution of uterus may be slow. Afterpain is more troublesome. Information, education and service of family planning should be given.
The mother also instructed on the care of babies, maintenance of body, personal hygiene and prevention of infection as well as the need for exclusive breast feeding.
Multiple Pregnancy Complications
Although having multiple pregnancy is a blessing highly desired by most women, yet this type of pregnancy is associated with enormous potential complications if not properly managed result in more maternal and perinatal mortality. This why twin pregnancy is often obstetrically referred to as abnormal pregnancy.
These may be divided into: complications of multiple pregnancy in mother and complications of multiple pregnancy in fetus.
Complications of multiple pregnancy in mother
Complications of multiple pregnancies in fetus
To manage delay interval birth of second twin, (1) rub up uterine contractions as well as putting the first twin to breast to trigger uterine activity via release of oxytocin; (2) If there is no obstruction, start oxytocin infusion or forceps delivery may be used; and (3) if obstructed, seek medical aid for immediate Caeserean section.
The bottom line
There is increased perinatal morbidity and mortality in multiple pregnancy and in singletons. Every woman should endeavour to book antenatal care on time and to receive care from skilled health care providers only. This would help in reducing the complications associated with twin pregnancy.
Note: One fetus may be died and be retained in uterus until term, when it will be expelled with the placenta as a flattened paper like fetus called a fetus papyraceous. Twin babies are small and often preterm.