CHAPTER I: INTRODUCTION

1.1. Background

Two or more babies can be conceived at the same time in a single woman. The most common type of multiple pregnancy is when two foetuses develop simultaneously in the uterus.[1]. It could be a dizygotic twin or a monozygotic twin. Worldwide, twin pregnancies are regarded as high-risk pregnancies with varying frequencies.[2].

As it comes to prematurity, fetal abnormalities, and growth limitation, twin births are associated with a higher risk of perinatal mortality as compared to singleton pregnancies. When twins are monochorionic (MC) rather than dichorionic (DC), the total risk of foetal death is approximately ten times higher. The main cause of this elevated risk is twin-to-twin transfusion syndrome or foetal growth retardation, which are the outcomes of placental and vascular sharing issues in an MC placenta.[3].

Worldwide, multiple pregnancies rate is on the rise  [4,5]. According to the National Vital Statistics Report for Births, the twin delivery rate was 33.7 per 1000 total births in 2013[4,5]. In East, Southeast, and Southern Asia, India, and Oceania, the prevalence rate is less than 8 twin pregnancies per 1,000 births; in the United States and Latin America, it ranges from 9 to 16 per 1,000 births[6].

A study done in France revealed that MC pregnancies had three times more medical terminations than DC pregnancies (1.67% vs 0.51%, p <0.001) while there were three times more stillbirths in MC than in DC pregnancies (10.09% vs 3.78%, p <0.001)[7]. A study conducted in Rome found that preterm birth (p < 0.008), twin-twin transfusion syndrome (TTTS) (p < 0.021), intrauterine growth restriction (IUGR) (p < 0.05), lower newborn birth weight (p < 0.05), and poorer Apgar score were all more common in MC twin pregnancies.[8]. A study in London found that the incidence of preeclampsia in MC and DC twin pregnancies to be 9.4% (95% CI, 5–13%)and 7.3% (95% CI, 5–9.6%) respectively[9].

The highest occurrence of twins, with an average twinning rate of 20 per 1000 deliveries, is found in sub-Saharan Africa[2,10]., with reports of up to 54 births per 1000 in Nigeria[11]. An investigation conducted in the Yaoundé Teaching Hospital in 1998 found that the prevalence of twin pregnancies in Cameroon was 1.8%[12]. According to a study in 2018 on the mother and foetal outcomes of twin pregnancies conducted in Bamenda, Cameroon, the prevalence of twin pregnancies was 2.8%[2].

1.2. Problem Statement

Both in developed and emerging nations, the frequency of multiple pregnancies has increased throughout the last 20 years[2,13]. Perinatal morbidity and mortality rates are influenced by chorionicity; for example, perinatal mortality rates are 50% in monoamniotic twins, 26% in monochorionic diamniotic twins, and 9% in dichorionic diamniotic twins[14]. When monochorionic (MC) twins are compared to dichorionic (DC) twins, the total risk of foetal death is around ten times greater[3].

In Cameroon the prevalence of twin pregnancy has increased (1.8% vs 2.8%) over the past two decades[2,12]. But very little is known regarding the influence of chorionic properties on these pregnancies.

1.3. Rationale/ Justification

Compared to singleton pregnancies, twin pregnancies are more likely to result in perinatal death, particularly due to prematurity, foetal abnormality, and growth retardation. Compared to dichorionic (DC) twin pregnancies, the total risk of foetal death in monochorionic (MC) pregnancies is almost ten times higher.[3]. These adverse outcomes have a psychological impact on the mothers and families concerned and also financial burden due to longer hospital stay.

Research on the outcomes of multiple pregnancies in mothers and foetuses has been conducted in Cameroon; however, the impact of chorionic characteristics on these outcomes has not been examined[2,12].

This study titled “Effects of chorionic properties on foetal outcomes amongst twin pregnancies in two hospitals in Bamenda; a comparative study” will contribute to knowledge and understanding of the condition which will help in the management and reduce complications to mother and the child. It will also serve as baseline material for further research.

1.4. Research Goal

The aim of this study was to enhance the knowledge on twin pregnancies especially the impact of chorionicity on the foetal outcomes of these pregnancies and propose strategies based on the results to help better the management of these pregnancies.

1.5. Research Question

What is the effect of chorionic properties on foetal outcome of twin gestations at the Bamenda regional hospital and Nkwen Baptist hospital?

1.6. Research Hypothesis

Adverse foetal outcomes are more likely to occur in monochorionic twin pregnancies than with dichorionic twin pregnancies in Bamenda.

1.7. Research Objectives

1.7.1. General Objectives

To evaluate the effects of chorionic properties on foetal outcome amongst twin gestations in two hospitals in the Bamenda health district.

1.7.2. Specific Objectives

1. To determine the prevalence of Twin pregnancies.
2. To describe the socio-obstetrical characteristics of women with twin pregnancies.
3. To compare the foetal outcomes of monochorionic and dichorionic twin pregnancies.
4. To determine the factors associated with adverse foetal outcomes of twin pregnancies.