Influence of Prematurity and Sex on the Health of a Child: A Transdiscliplinary Approach

By Yves Tremblay

The document that you are about to access, deals with the many facets of prematurity. More precisely, it addresses the following issue: the influence of prematurity and sex on the health of a child. This work is the fruit of close collaboration between several disciplines engaged in a transdisciplinary endeavour. Starting with biomedical knowledge, we have attempted to integrate knowledge from the fields of psychology, ethics, epidemiology and law. This book is based on the knowledge gained from an online forum but was written with the idea of making its content accessible to everyone interested in the subject. It could also serve as food for thought by parents who have a premature baby or even future parents in general. This research question, presented in all its complexities, will also be of interest to researchers and clinicians in training.

• Language: English
• Publisher: BookBaby
• Release date: Dec 5, 2013
• ISBN: 9781483515427

Book preview

disciplines.

INTRODUCTION

Over the course of the past few decades, a growing number of infants born prematurely have survived. The progress of paediatric medicine now allows completion, often successfully, of the maturation of the body of the newborn outside the maternal womb. While many people, when asked about the events occurring in the perinatal period, speak of a miracle, others proclaim instead that the so-called heroic measures involved are overly aggressive for such tiny patients.

Whether in informal discussions, or in the media, the acceptability of helping such under-developed beings to survive raises many questions. As such, prematurity, its associated risks of severe disabilities for the child, and permanent disturbance of the life of the parents are subjects that affect a large number of people. Viewpoints often conflict, but do not always rely on sufficient knowledge of the inherent factors of the problem.

In order to better understand the complex reality of prematurity, people of various disciplines¹ have contributed their knowledge and have endeavoured to integrate them into a synthesis that takes into account the complexity of a delicate question: What are the parameters to be taken into consideration in the choice to help a child born at the limit of viability survive or not? In addition, due to scientific and medical indications that point towards a poorer prognosis in boys, would there be an ethical problem with providing parents with different information depending on the sex of the child"?

Rising to the challenge of integrating knowledge from various domains, the authors drew inspiration from a method previously used by Lambert & Monnier-Barbarino (2005). This method uses an online forum platform where practitioners from various disciplines meet to give their opinion according to the state of knowledge in their respective field of expertise. First, each participant submits a document that expresses his opinion regarding only his discipline. Then, each participant reads each of the other documents submitted to the forum to achieve a view that goes beyond the strict framework of his own knowledge and expertise. Finally, the participants achieve a more comprehensive view of the problem.

The first synthesis proposed focuses on epidemiology, which paints a portrait of the most common causes of premature childbirth as well as its associated risk factors. The biomedical chapter explores the underlying mechanisms of prematurity. It also deals with the physiological consequences of prematurity, particularly the respiratory distress syndrome (RDS) which is frequently encountered in the premature infant and which deserves special attention, insofar as sex plays an important role in the outcome of the development of the premature infant. The chapter dealing with the psychological aspects focuses on the impacts on the psychosocial development of the premature infant. Emphasis is put on the variable of cognitive and academic development of the premature infants, from newborn to adult. It also deals with the emotional and mental health aspects which may differ in premature infants, compared with infants born at term. For its part, the document relating the ethical aspects, discusses the morals and values involved with regards to decisions that are made in the context of the resuscitation of a premature infant. The author also endeavours to better define the place of parents in this difficult process. Lastly, the law chapter defines the legal context and ramifications linked to the decision-making process of whether or not to resuscitate a premature infant. More specifically, the legal chapter addresses the notion of the legal status of the premature infant, the rights and responsibilities of the parents, as well as those of the physicians.

Finally, a transdisciplinary analysis is presented, which renders a better account of the complex reality of prematurity, the decisions that it involves and the possible consequences of those decisions, and which covers all of the issues addressed individually.

¹ The expertise of these participants will be presented at the beginning of each chapter.

Influence of prematurity and sex on the health of a child

CHAPTER I: EPIDEMIOLOGICAL PARAMETERS OF PREMATURITY

By:

Stéphanie Roberge

AUTHOR’S PRESENTATION

Stéphanie Roberge is a master’s degree student of epidemiology at Laval University under the direction of Dr. Emmanuel Bujold and Dr. Yves Lacasse. Her subject of study focuses on the role of the sex of the fetus in response to treatments in women at risk for premature delivery. Her research experiences and her dissertation have allowed her to specialize in meta-analysis. In addition, her bachelor’s degree in anthropology from the University of Montreal obtained in 2007 has been useful to her in the integration of diverse knowledge, which helps her to continue her doctorate research in perinatal health.

AUTHOR’S ACKNOWLEDGMENTS

I would like to thank Dr. Bujold and Dr. Lacasse who agreed to direct me in my master’s degree project. Dr. Bujold gave me an incredible chance to familiarize myself with and integrate myself into the environment of perinatal health; his enthusiasm and projects have given me desire to continue in this field. I would also like to thank my work colleagues, the participants and mentors of the forum who have allowed me to learn more through enriching exchanges.

INTRODUCTION

Premature childbirth is a major issue of pregnancy, because it is associated with an increased risk of morbidity and mortality in the mother and the fetus (table 1) [1]. Improvements in health care and the increase in obstetrical interventions in recent years have influenced the number of babies born very prematurely (<32 weeks of pregnancy) [2]. When it is a matter of deciding to resuscitate an infant born at the limit of viability (22–24 weeks of pregnancy), several parameters must be considered, including epidemiological parameters, because the decision may have several potential consequences: death of the infant, significant morbidity including neurological developmental anomalies, or even cerebral palsy, etc. We believe that some couples would want all resuscitation measures to be offered in order to give their child the best chance at survival, regardless of the consequences. Others, however, may be hesitant to pursue these same resuscitation measures in a child with a substantial risk of long-term repercussions.

In this document, efforts will be concentrated on identifying the factors that can influence perinatal health as well as epidemiological resources available to help research and decision-making. Particular attention will be focused on the sex of the child, in order to understand the influence and the place that this parameter has in extreme prematurity. Factors will be separated into two subgroups: those related to the mother and those related to the child. Parameters related to prematurity will be highlighted through epidemiological studies that have allowed the dynamic state of these health problems in the population to be monitored.

PARAMETERS RELATED TO THE MOTHER

From an epidemiological point of view, the cause of a health event is an incident, condition or characteristic that is necessary for its occurrence if the required conditions are present. Health events are rarely attributable to a single, necessary and sufficient cause, and the main causes can be composed of subjacent causes.

In a field as complex as prematurity, it is important to understand that each risk cannot be measured, because preterm birth can result from a very great number of causes, some of which will probably remain unknown. The main known causes of prematurity are induced preterm delivery (for maternal and/or fetal reasons, such as pre-eclampsia), preterm labour (PTL) (with intact membranes) and preterm premature rupture of membranes² (PPROM) (figure 1). Premature rupture of membranes (PROM) is the cause of about one third of premature births. It is associated with a significant increase in pulmonary, ocular, cerebral and motor morbidity related to prematurity [7].

Figure 1. Causes of prematurity [8]

Gestational age is one of the most determinant factors for a newborn’s chances of survival. From 22 weeks of gestation, there is a significant reduction in mortality rate with increased gestational age at birth. Thus, the more premature the babies are born, the lower their chances of survival. In the United States, the survival rate of an infant born between 32 and 35 weeks of pregnancy is 98% compared with 90–95% for infants born between 28 and 31 weeks, 87% for those born at 27 weeks and 80% for those born at 26 weeks [9]. The reduction continues markedly from this point; infants born generally around 22 to 24 weeks of pregnancy are thus considered to be at the limit of viability. Neonatal survival rate varies between 11% and 30% at 23 weeks of pregnancy, from 26% to 52% at 24 weeks of pregnancy, and from 54% to 76% at 25 weeks of pregnancy [10, 9] (table 2).

One of the main maternal and fetal complications is due to hypertensive disorders [2]. Pre-eclampsia is a complication of pregnancy defined as the combination of de novo³ gestational hypertension and proteinuria.⁴ Its prevalence according to country varies between 3% and 18% [11]. It is one of the most significant causes of perinatal mortality in the world. Pre-eclampsia is characterized by poor placental implantation, which can lead to intra-uterine growth retardation, and other complications such as acute lung edema, placental detachment, hepatic dysfunction, maternal convulsions, and even death [12]. The only definitive treatment for pre-eclampsia is delivery. In recent years, the use of an ultrasound technique (Doppler) enables early diagnosis of placental anomalies as well as the prediction of the risk of pre-eclampsia [13, 14]. Unfortunately, few therapeutic or preventive tools are currently available.

In Canada, the average age of women at childbirth is constantly increasing. Advanced maternal age, defined as an age greater than 35 years at the time of childbirth, is associated with an increase in several complications of pregnancy including premature childbirth, hypertensive pregnancy disorders, gestational diabetes, and lastly, a significantly increased risk of fetal aneuploidy,⁵ such as Down’s Syndrome (trisomy 21) [15, 16, 17] (table 3). Although advanced maternal age is associated with increased premature deliveries, there is no clear evidence that maternal age is a risk factor for neonatal morbidity in extremely premature infants [18].

A significant proportion of premature deliveries before 32–34 weeks are associated with a microbial invasion (infection) of the amniotic cavity (MIAC) [19-23]. Although the amniotic cavity is a normally sterile space, an MIAC, diagnosed by amniocentesis, is present in more than 15% of patients with premature labour, and in 30% to 50% of those who deliver prematurely [24]. The earlier the delivery occurs, the higher the chances of finding an MIAC [25]. In women who present with preterm premature rupture of membranes (PPROM), the MIAC rate is even higher, ranging from 30% to 70% [26, 27]. Since the majority of microorganisms found in the amniotic fluid are part of the genital microbial flora of the woman, it is most likely an ascending infection, coming from the genital tract, which extends to the chorioamniotic membrane, to the amniotic fluid, and potentially to the fetus. Recently,