EMGO Institute for Health and Care Research

Quality of Care

Underweight pregnant women in low risk populations: Does a low BMI (<18.5) predict adverse pregnancy outcomes?

Paul de CockAIRC2012

• Midwifery Academy Amsterdam

Groningen (AVAG)

• VU University Medical Center

Echelon system in perinatal care

The Netherlands: echelon system in perinatal care

• 1st: community: monitored by independent midwife

• 2nd: hospital: gynaecologist & clinical midwife

• 3rd: academic referral centre: gynaecologist & clinical midwife

http://www.knov.nl/docs/uploads/Midwifery_in_The__Netherlands__20120730__groot.pdf

Midwifery care

• App. 184000 births in Netherlands

• A quarter of these are home births

• Antenatal care by Midwife in 79.6% of pregnancies

• Remaining pregnancies (20.4%) are under supervision of gynaecologist (hospital/secondary care)

– Half of these are because of a medical indication.

Risk selection in echelons

• Women with health complications or known health risks are referred to secondary care setting

• This means that there is a risk selection in primary care, which is effective.

• For low BMI women this means that only those with no known additional health risks are under supervision of a primary care midwife.

Reason for this research

• University of applied science keeps strong links with the field – the field is actively invited to submit research questions to the college

• Manager of a large midwifery practice asked about the risks attached to low BMI for pregnant women under supervision of a primary care midwife.

– Women with medical indications have been referred. Is there a risk for the remaining healthy low BMI women with regard to pregnancy outcomes for mother and baby?

Low BMI – risk

• Increased risk of miscarriage (Maconochie et al., 2007)

• Preterm birth (Han et al., 2011)

• Low birth weight (Han et al., 2011)

• Increased risk of anaemia (Sebire et al., 2007)

Low BMI – lowered risk of…

• Reduced risk of complications, such as:– Gestational diabetes mellitus

– Pre-eclampsia

– Obstetric intervention

– Postpartum haemorrhage

(Sebire et al., 2007 - BMI<20)

Low BMI in low-risk population

• Research question:

– What are the pregnancy outcomes of low-risk underweight women in primary midwifery care?

Method - sample

• Retrospective case-control database study

– 2 large midwifery practices

– All underweight (< 18.5) women on record (past 5 years)

– Controls matched on age, smoking, alcohol use, drug use

– Only controls with normal BMI were included (18.5 – 24.99)

Method - outcomes

• Maternal

– Hypertension

– Hb (1st consult and at 30 weeks)

– Suspected intrauterine growth retardation

• Birth outcomes

– Duration of pregnancy

– Prematurity

– Instrumental delivery

– Bloodloss

– Active management of placental delivery

Method - outcomes

• Neonatal

– Weight

– Weight percentile (<2.3; <5.0; <10)

– APGAR <7 after 5 minutes

– Consult with paediatrician

Results – Pregnancy outcomes

  Low BMI (<18,5) Normal BMI (>18,5-24,99)

P-value

Hypertension yesno

1156

0157

-

Hb 1st consult (mmol/l) 7,54 7,74 <0,05*

Hb 30 weeks (mmol/l) 7,09 7,29 <0,05*

Hb 1st consult <7,1 mmol/l yesNo

 30127

 17140

0,058

Hb 30 weeks <6,3 mmol/lyesno

 11146

 3154

<0,05*

Consulted obstetrician during pregnancyyesno

 

43115

 

29128

0,099

Suspected IUGRJa Nee

 11146

 9148

0,655

Disturbed glucose levelsJaNee

 1156

 3154

0,317

Results – Birth outcomes

  Low BMI <18,5 Normal BMI (>18,5-24,99)

P-value

Gestation (days) 277,38 277,80 0,840Prematurityyesno

8149

 8149

1,000

Instrumental deliveryyesno

 23134

15142

0,194

Total blood loss (ml) 403,67 389,81 0,717Active management of placental deliveryyesnonot known

 

1004314

 

106474

 

0,6760,673<0,05*

Results – Neonate outcomes

  Low BMI <18,5 Normal BMI (>18,5-24,99)

P-value

Genderboygirl

8869

 7681

0,349b0,327b

Birth weight (grammes) 2878,48 3532,68 <0,05*a

Birth weightpercentile

12,62 45,39 <0,05*a

Birth weightpercentile<2,3yesnosuspected IUGR

<5,0yesnosuspected IUGR

<10yesnosuspected IUGR

  441136 (13,6 %)

 

71868 (11,3%)

99589 (9,1%)

61511 (16,6%)  

121452 (16,7%)

171403 (17,6%)

  <0,05*b

<0,05*b

<0,05*b

APGAR score < 7 after 5 minutesyesno

  4153

  3154

 0,705b

Consulted Peadiatricianyesno

 31126

 43114

0,198b 

Discussion

• Women with low BMI at increased risk of anaemia.

• Babys are smaller, but no raised levels of suspected IUGR, poor APGAR scores or consults with paediatrician.

• No difference in prematurity found in this study

Conclusion

• On the basis of this study pregancy outcomes do not appear to differ much between women with low and normal BMI in primary care.

• More research is being done in a large prospective cohort study (DELIVER) to assess a broader range of outcomes in a large national sample.

• Paul de Cock PhD ab, Willemijn Perdijk b, MA RM, Aresh Mohammadi BA RM b, Elise Neppelenbroekb, Ingrid Hollemab

Thank you for listening

• a Department of Midwifery Science, AVAG and the EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands, p.decock@vumc.nl.

• b Midwifery Academy Amsterdam Groningen, The Netherlands; T: +31 50- 3618886, F: + 31 50-3619930,