Perinatal epidemiology Flashcards
what is meant by perinatal
around the time or birth
ICD10 definition = 22 completed weeks of gestation to 7 completed days after birth
when does WHO say the perinatal period ends
28 weeks of gestation or when the fetus weighs 1000g to the end of the 7th completed day
how does the NHS define perinatal
the time between conceiving a baby until the end of the first postnatal year
what is the importance of perinatal epidemiology
identifying effects of events during pregnancy, outcome, maternal fetal and neonatal health outcomes
can identify harmful exposures during pregnancy, diet, genetic constitution, the effects of illness and medications
increased evidence that adverse experiences during pregnancy can impact childhood and adult health
what is the fetal origins hypothesis
Barkers 1995
says undernutrition in the womb during middle-late pregnancy causes improper fetal growth and so predisposition to diseases in adulthood
what is meant by fetal programming
events occurring during critical points of pregnancy may cause permanent effects on fetus and infant long after birth
what are methodological challenges to consider when using randomised control trial in perinatal research
randomising women
recruitment
factors like age, ethnicity, genetic constitution
inclusion of multiple births and subsequent births from the same mother
how do calculate perinatal prevalence rates
total birth prevalence = no. cases / no. births (live and still
how to find number of births for calculating prevalence
LB + FD + IA
live born
fetal deaths from 20 weeks gestation
IA - induced abortion or termination of pregnancy
what is perinatal mortality
number of stillbirths and deaths in the first week of life per 1000 live births
what is a stillbirth
a baby born dead after 24 completed weeks of pregnancy
before this is a miscarriage
5 in 1000 births in the Uk are still
stillbirth rates in most industralised countries have declined over the past 20 years
outline neonatal death
deaths among live born infants prior to first 28 days of life, per 1000 live births
what is ENMR
early neonatal mortality = deaths 0-6 days
what is LNMR
late neonatal mortality
= deaths 7-28 days
what is post neonatal mortality
deaths among live born infants between 29 days of life to the end of the first year of life per 1000 live births
what did Shenyang show for neonatal death between 1997 and 2014
urban neonatal mortality rate was lowest compared to rural neonatal mortality rate which was highest
per 1000 live births
what can perinatal mortality be used as
a public health indicator to assess the populations health status
effective way to compare public health between populations and over time
compare perinatal and antenatal health care between countries
what are factors undepinning perinatal death burden
genetics
environment
diagnostic services
methods of data collection
termination of pregnancy
what are some health and survival challenges to the fetus
abnormal placentation
poor nutrition
multiple births
congenital abnormalities
infection
these can lead to stillbirth
why is the rate of twins increasing
due to increasing maternal age and assisted reproductive technologies
outline the global burden of congenital abnormalities
2-3% of babies born with significant congenital anomaly
major cause of stillbirth, infant mortality, childhood morbidity and long term disability
outline genetics as a cause of congenital anomaly
abnormalities of large portion or entire chromosome
inheritance of abnormal genes
sporadic mutations in one of the germ cells contributing to fetus
outline teratogenic exposure as a cause of congenital anomaly
in intrauterine environment of fetus
- dietary deficiency e.g maternal folic acid associated with increased risk of spina bifida
- toxic effects - exposure to harmful substance during pregnancy e.g thalidomide, mercury
- maternal infection e.g rubella and syphilis
what can the zika virus cause
microcephaly
below average head size of baby, often caused by failure of brain to grow at normal rate
affects 25,000 babies in US each year
what was the rate of stillbirths in 2020
3.8 stillbirths per 1000 births - unchanged since 2019
what is the reason for lack of decline in stillbirth rates
unknown but may be related to changes in the distribution of risk factors
e.g greater numbers of births to very young and older women, increase in obesity and diabetes
how many neonatal deaths are there worldwide
4 million
what are the main causes of neonatal death
preterm birth - 28%
infections - 26%
asphyxia - 23%
tetanus - 7%
what are some consequences of challenges to the fetus
premature delivery
low birth weight
cerebral palsy
gastroschisis
neonatal death
what are common infectious diseases associated with fetus
respiratory tract infection
adenovirus
pneumonia
what is the rate of preterm birth
5-7%
large ethnic variation
interventions have limited success
genetic suscpetibility factors believed to be important
what are the consequences of preterm birth
patent ductus arteriosus (PDA) - delay of closure to blood vessel diverting blood from lungs
developmental delay
respiratory distress
neonatal mortality
importance of nutrition to catch up growth
what is the leading cause of illness and death in mothers and new born babies
late pregnancy
19% of all first pregnancies affected
what are 3 diseases of late pregnancy
- pre-eclampsia - severe high BP, risk of stroke and seizure - 5% of first time mothers
- fetal growth restriction - due to placenta problems leading to inadequate nutrition - 1 in 10 pregnancies
- pre-term labour - long term disability, high morbidity and mortality
what are causes of low birth weight
alcohol consumption
increased chorioaminonitis
cocaine use
increased multiple births
preterm induction of labour
what is cerebral palsy
group of non-progressive neurological disabilities in development of human movement and posture
arises from disturbance in fetal brain development
no decline over past 60 years
what are the 2 types of cerebral palsy
congenital - during pregnany - 75%
acquired - after birth - 25%
what is the incidence of cerebral palsy
2.5 per 1000 live births
what are some known causes of cerebral palsy
80% of cases have unknown aetiology
infections, malnutrition, head injury in early childhood
what is gastroschisis
opening in abdominal wall causes bowel to develop outside of babys stomach
occurs during 4th week of development due to lack of meeting between lateral body and walls of embryo
associated with young maternal age
what is the prevalence of gastroschisis
4 in 1000 new borns
what are risk factors associated with gastroschisis
low social class
smoking
alcohol consumption
medications
use of recreational drugs like cocaine
opioid use
in summary what are the causes of neonatal death
birth outcomes
obsteric and neonatal complications (injury, asphyxia, hypothermia)
maternal health preceding and during pregnancy
bacterial and viral infections
