Around 50% of women are overweight or obese when they become pregnant. Obesity in pregnancy increases the risk of complications for mothers and babies, including development of high blood pressure, diabetes in pregnancy, birth defects and having an emergency caesarean section. Smoking during pregnancy compromises the growth of the baby leading to early birth and low birth weight. There are healthcare recommendations to help women prepare for pregnancy to help improve outcomes for mothers and babies. Yet, dedicated care before pregnancy (pre-conception care) is not routinely available within the NHS.
Our aim is to find out more about obesity and smoking before and during pregnancy. These are factors which could be modified to help improve outcomes for mothers and their babies. We are particularly interested in finding out:
• The number of women with of pre-conception obesity and who smoke, how this has changed over time and varies by
factors such as ethic group and social deprivation
• The existing pre-conception care for women who are overweight/obese and for women who smoke
• The risk of pregnancy complications for these mothers and complications for the neonates
This research will help us to understand the current state of pre-conception care for women who are overweight/obese and/or smoke within the UK and how this varies by region and other factors such as social deprivation and ethnicity. Ultimately, gaining a better understanding of ways to improve health before conception will achieve better outcomes for mothers and babies.
Many pregnancy complications and adverse outcomes in infants are associated with social deprivation. Infant deaths are also related to prematurity, congenital disorders and infections. There are some potentially modifiable factors, including lifestyle factors that are associated with prematurity and infant mortality. Both adverse pregnancy complications and poor infant outcomes have been attributed to maternal overweight/obesity and smoking. While health improvement services are available during pregnancy, less is known about pre-conception care. It is important to have better estimates of smoking and obesity in the pre-conception period and to determine who is most at risk of having adverse outcomes so that appropriate interventions or strategies can be implemented to benefit women and their babies.
Objectives:
The objectives are to estimate the trends in the prevalence of pre-conception body mass index (BMI), smoking, and pre-conception care for women who are overweight/obese and/or smoke by calendar year (2005-2022), region, ethnicity, level of deprivation. Additionally, we will assess maternal and neonatal outcomes by BMI category and smoking status.
Study design and analysis:
Longitudinal cohort study of women age 15-50 years who have had at least one pregnancy. We will estimate the proportion of women who are overweight/obese (i.e. BMI ≥ 25 kg/m2), and who smoke and investigate how this varies over time and other factors such as ethicity, social deprivation and region.
We will also:
• Assess the existing pre-conception and pregnancy care for women who are overweight/obese and for women who smoke by factors such as age, ethnicity, social deprivation using logistic regression
• Assess the associations of BMI and smoking with risk of pregnancy complications mothers and the neonates using Cox regression
1. Pre-conception indicators:
• Pre-pregnancy BMI;
• Background demographics (age, ethnicity, quintiles of deprivation, number of pregnancies);
• Folic acid (including dose and timing of commencement);
• Pregnancy intention;
• Alcohol consumption;
• Smoking (including amount smoked);
• Referral for smoking cessation services;
• Weight loss intervention;
• Other co-morbidities (hypertension, diabetes, mental ill health etc.);
• BMI recorded at booking;
• Aspirin use (timing and dose);
• Vitamin D (timing and dose);
• Previous pregnancy loss;
• Previous obstetric complication (miscarriage, stillbirth, preterm delivery, pre-eclampsia);
2. Maternal and neonatal outcomes:
• Hypertensive disorders of pregnancy (gestational hypertension, pre-eclampsia);
• Gestational diabetes;
• Miscarriage;
• Stillbirth;
• Gestational age at delivery;
• Labour onset (Induction or labour / spontaneous onset);
• Mode of delivery;
• Postpartum haemorrhage;
• Shoulder dystocia;
• Birth weight (including birth centile);
• Infant mortality;
A full list of the clinical codes for the conditions is available here:
https://github.com/mumpredict/Read-codes-and-ICD-10-codes/tree/main/Rea…
These are in the process of being developed for SNOMED CT codes for CPRD Aurum.
Krishnarajah Nirantharakumar - Chief Investigator - University of Birmingham
Kelly-Ann Eastwood - Corresponding Applicant - University of Birmingham
Anuradhaa Subramanian - Collaborator - University of Birmingham
Francesca Crowe - Collaborator - University of Birmingham
Krishna Gokhale - Collaborator - University of Birmingham
Steven Wambua - Collaborator - University of Birmingham
Patient Level Index of Multiple Deprivation;CPRD Aurum Mother-Baby Link;CPRD Aurum Pregnancy Register;CPRD GOLD Mother-Baby Link;CPRD GOLD Pregnancy Register