ILLEGAL DRUG USE IN PREGNANCY
A 19-year-old woman is referred to the antenatal clinic by her general practitioner (GP). She is currently 22 weeks’ gestation in her second pregnancy. She had a son by normal vaginal delivery 18 months ago, who was taken into social services care initially and now lives with his grandparents (the father’s parents). Since then, the woman has been having very infrequent periods and only discovered she was pregnant when she attended the emergency department with a presumed urinary tract infection 2 weeks ago. At that stage abdominal palpation revealed a mass, and ultrasound scan confirmed the singleton gestation.
The GP letter informs that the woman has been a user of crack cocaine and heroin in the past but that she has been on a methadone replacement programme for the last 8 weeks. The current prescribed regime is 60 mL methadone, which she collects daily from the pharmacist.
The woman reports that she still injects street heroin several times per week but has not used crack cocaine for several months. She says that she drinks minimal alcohol but she smokes 20–25 cigarettes per day.
There is no other medical history of note.
She lives in a council flat with her partner who is also taking prescribed methadone. She denies any domestic violence within the relationship.
The woman appears thin and anxious. The blood pressure is 107/65 mmHg and pulse 90/min. The abdomen is distended with the fundus palpable at the umbilicus. The fetal heartbeat is heard with a hand-held Doppler device.
· What other investigations should be arranged?
· What are the risks associated with drug use in pregnancy?
· How would you manage this woman during the pregnancy?
The woman has been found to be hepatitis B surface antigen positive. This needs further investigation withe antigenicity to determine risk of transmission, and liver function tests. Assuming the hepatitis B is related to needle sharing, she is also at significant risk of hepatitis C and this should also be tested for at this stage.
A urine toxicology screen should be performed with the woman’s consent, to confirm the drug history she has given and what the risks to the fetus may be.
Most units have a specialist team for management of drug-using women in pregnancy. This should include specialists in substance misuse, a social worker, a specialist midwife and an interested obstetrician.
The woman needs to be encouraged to engage more fully with the methadone replacement programme. This may well mean increasing the methadone regime to allow her to stop the street heroin. Once this has been achieved then she can gradually reduce the dose needed, with appropriate support. It is better to be still taking a maintenance dose of methadone through the pregnancy than to try and stop too quickly, resulting in unquantifiable amounts of illegal drugs being taken during the pregnancy.
The fetus should be assessed for growth during the pregnancy in view of the increased risk of intrauterine growth restriction.
Labour should be managed as for any non-drug-using woman. The difference may be that the usual doses of opiates needed for analgesia (epidural or systemic) may be insufficient and need to be titrated up to ensure adequate pain control.
Fetal blood sampling should be avoided in labour due to the risk of vertical transmission of hepatitis B antigen.
The baby should be administered hepatitis B immunoglobulin at delivery and be given the accelerated hepatitis B immunization course.
Babies of opiate-using mothers may have initial respiratory depression as a result of the opiates but then develop withdrawal symptoms. They need immediate transfer to the neonatal unit for management of the symptoms, with reducing doses of opiates.
Issues of care for the baby should be established between the social services, medical team and the parents, prior to delivery.