Why focus on preterm birth?
Long-term outcomes | Examples: | Frequency in survivors: | |
---|---|---|---|
Specific physical effects
| Visual impairment | • Blindness or high myopia after retinopathy of prematurity • Increased hypermetropia and myopia | Around 25% of all extremely preterm affected[80] Also risk in moderately preterm babies especially if poorly monitored oxygen therapy |
Hearing impairment | Up to 5 to 10% of extremely preterm[81] | ||
Chronic lung disease of prematurity | • From reduced exercise tolerance to requirement for home oxygen •Increased hospital admissions in childhood for LRTI[82] | Up to 40% of extremely preterm[83] | |
Long-term cardiovascular ill-health and non-communicable disease | • Increased blood pressure • Reduced lung function • Increased rates of asthma • Growth failure in infancy, accelerated weight gain in adolescence | Full extent of burden still to be quantified | |
Neuro-developmental/ behavioral effects[84] | Mild Disorders of executive functioning | • Specific learning impairments, dyslexia, reduced academic achievement | |
Moderate to severe Global developmental delay | • Moderate/severe cognitive impairment • Motor impairment • Cerebral palsy | Affected by gestational age and quality of care dependent[85] | |
Psychiatric/ behavioral sequelae | • Attention deficit hyperactivity disorder • Increased anxiety and depression | ||
Family, economic and societal effects
| Impact on family Impact on health service Intergenerational | • Psychosocial, emotional and economic • Cost of care[7] - acute, and ongoing • Risk of preterm birth in offspring | Common varying with medical risk factors, disability, socioeconomic status[86] |
Understanding the data
Preterm birth -- what is it?
Defining preterm birth
Preterm birth - why does it occur?
Type: | Risk Factors: | Examples: | Interventions:* |
---|---|---|---|
Spontaneous preterm birth:
| Age at pregnancy and pregnancy spacing | Adolescent pregnancy, advanced maternal age, or short inter-pregnancy interval | Preconception care, including encouraging family planning beginning in adolescence and continuing between pregnancies |
Multiple pregnancy | Increased rates of twin and higher order pregnancies with assisted reproduction | Introduction and monitoring of policies for best practice in assisted reproduction | |
Infection | Urinary tract infections, asymptomatic bactiuria, malaria, HIV, syphilis, chorioamnionitis, bacterial vaginosis | Sexual health programs aimed at prevention and treatment of infections prior to pregnancy. Specific interventions to prevent infections and mechanisms for early detection and treatment of infections occurring during pregnancy. | |
Underlying maternal chronic medical conditions | Diabetes, hypertension, anaemia, asthma, thyroid disease | Improve control prior to conception and throughout pregnancy | |
Nutritional | Undernutrition, micronutrient deficiencies | ||
Lifestyle/work related | Smoking, excess alcohol consumption, recreational drug use, excess physical work/activity | Behavior and community interventions targeting all women of childbearing age in general and for pregnant women in particular through antenatal care with early detection and treatment of pregnancy complications | |
Maternal psychological health | Depression, violence against women | ||
Genetic and other | Genetic risk, e.g., family history Cervical incompetence Intra-uterine growth restriction Congenital abnormality | ||
Provider-initiated preterm birth:
| Medical induction or cesarean birth for: | Prior classical cesarean section, Placenta accrete. | In addition to the above: Programs and policies to reduce the practice of non-medically indicated induction of labor or cesarean birth |
obstetric indication Fetal indication Other - Not medically indicated | There is an overlap for indicated provider-initiated preterm birth with the risk factors for spontaneous preterm birth |
Preterm birth--how is it measured?
Assessing gestational age
Accounting for all births
Method | Accuracy | Details | Availability/feasibility | Limitations |
---|---|---|---|---|
Early ultrasound scan
| +/- 5 days if first trimester +/- 7 days after first trimester | Estimation of fetal crown-rump length +/- biparietal diameter/femur length between gestational age 6 - 18 weeks | Ultrasound not always available in low-income settings and rarely done in first trimester | May be less accurate if fetal malformation, or maternal obesity |
Fundal Height
| ~ +/- 3 weeks | Distance from symphysis pubis to fundus measured with a tape measure | Feasible and low cost | In some studies similar accuracy to LMP Potential use with other variables to estimate GA when no other information available |
Last menstrual period
| ~ +/- 14 days | Women's recall of the date of the first day of her last menstrual period | Most widely used | Lower accuracy in settings with low literacy. Affected by variation in ovulation and also by breastfeeding. Digit preference |
Birthweight as a surrogate of gestational age
| More sensitive/specific at lower gestational age e.g. <1500 g most babies are preterm | Birthweight measured for around half of the world's births | Requires scales and skill. Digit preference | |
Newborn examination
| ~ +/- 13 days for Dubowitz, higher range for all others | Validated scores using external +/or neurological examination of the newborn e.g. Parkin, Finnstrom, Ballard and Dubowitz scores | Mainly specialist use so far. More accurate with neurological criteria which require considerable skill. Potential wider use for simpler scoring systems | Accuracy dependant on complexity of score and skill of examiner. Training and ongoing quality control required to maintain accuracy |
Best obstetric estimate
| Around +/- 10 days (between ultrasound and newborn examination) | Uses an algorithm to estimate gestational age based on best information available | Commonly used in high-income settings | Various algorithms in use, not standardized |
Using the data for action
Preterm birth rates--where, and when?
Global, regional and national variation of preterm birth for the year 2010
Preterm births time trends 1990 to 2010
Priority policy and program actions based on the data
Actions to improve the data
Definition consistency | Numerator (number of preterm births) |
---|---|
Consensus on definition of preterm birth for international comparison, specifying gestational age | Simplified, lower cost, consistent measures of gestational age (GA) Widespread use and recording of GA |
Consistent inclusion of all live births of all gestations or weight, and noting if singleton or multiple births and noting the proportion that are under 500 g/22 weeks and under 1,000 g/28 weeks for international comparison Also record all stillbirths from 500 g/22 weeks and 1,000 g/28 weeks (whilst collecting by other national definition for stillbirth if different e.g., 20 weeks in United States) | |
Denominator (number of births)
| |
Consistent measurement of all live births of all gestations noting if less than 22 weeks and if singleton or multiple births | |
Also record all stillbirths | |
Actions to improve the data
|
Focus on capture and consistency:
|
Gestational age and birthweight recording for all births | |
Improve reporting of neonatal cause of death with preterm as direct cause and as risk factor (counting deaths of preterm babies who die from other causes) | |
Collection of impairment data e.g., cerebral palsy and retinopathy of prematurity (ROP) rates according to a basic minimum dataset to increase consistency | |
For settings where additional capacity available: | |
Improve measurement e.g. gestational age assessment using early, high-quality ultrasound scan, development and refinement of improved gestational age assessment tools for use in low-resource settings | |
Increase the granularity of the data:
| |
Record if provider-initiated, e.g., cesarean birth, or spontaneous and the basic phenotype, e.g. infection/relative contribution of each cause especially multiple births | |
Improve the linkage of data to action: e.g., collating data by gender, socioeconomic status, ethnicity, subnational e.g. state | |
Impairment data according to a more comprehensive standard dataset | |
Data for action
| Set goals for national and global level for |
1. Reduction of deaths amongst preterm babies by 2025 | |
2. Reduction of preterm birth rates by 2025 | |
Regular reporting of preterm birth rates and preterm-specific mortality rates at national level and to global level to track against goals |