BACKGROUND AND PURPOSE:

• Approximately 11-25% of women move during pregnancy
• Moving during childhood may be associated with risk for adverse outcomes; however, insufficient data exists related to perinatal period
• Bond et al. (BMJ, 2019) investigated the association between a residence change during the first trimester of pregnancy and adverse infant outcomes (low birth weight, preterm birth, and small for gestational age)

METHODS:

• Population-based cohort study (2007 to 2014)
• Participants
  • Singleton births | Maternal age ≥18 years (age cohort used to exclude those who may have additional stressors due to teen pregnancies)
• Groups
  • Movers: Residential move during first trimester of pregnancy
  • Non-Movers: women who did not move during first trimester
• Data analysis
  • Non-Movers matched 4:1 to movers
  • Risk ratio (RR) were adjusted for the following: Maternal age | Race | Marital status | Parity | Education | Smoking |Income | Health insurance payer
  • Power analysis: 80% power | Alpha=0.05 | Sample size of 22,000 movers
• Primary outcomes
  • Low birth weight: <2500 g at birth
  • Preterm birth: <37 weeks
  • SGA: BW in the lowest 10% of birth for GA and fetal sex

RESULTS:

• 28,011 women in the Movers group | 12,367 women in the Non-Movers group
• Moving in the first trimester was associated with
  • Increased risk of low birth weight
    • 6.4% vs 4.5%
    • adjusted RR 1.37 (95% CI, 1.29 to 1.45)
  • Increased risk of preterm birth
    • 9.1% vs 6.4%
    • Adjusted RR 1.42 (95% CI, 1.36 to 1.49)
  • Additional preterm births that could be attributed to moving vs not moving
    • Additional 24 preterm births per 1000 births
    • Adjusted risk difference: 2.40 per 100 (95% CI, 2.04 to 2.76)
  • Slight increased risk of small for gestational age
    • 9.8% vs 8.7%
    • Adjusted RR 1.09 (95% CI, 1.00 to 1.09)
  • Results were consistent for low birth weight and preterm birth across all socioeconomic strata

CONCLUSION:

• A residential move during the first trimester of pregnancy may be a risk factor for preterm birth and low birth weight
  • Potential causes: Disruption of healthcare and social support | Physical strain
  • Consider including moving question on first visit intake form to identify those who may be at risk, and offer stress mitigation strategies and ensure continuity of care during the move
• However, Nathan Hodson’s BMJ blog post (BMJSRH) on the subject cautions readers to remember that
  • This study focuses on RR rather than absolute risk differences which remain small and majority of women in this study who experience preterm labor would have labored prematurely regardless of moving
  • There may be significant benefits to a move (e.g., safer neighborhoods, closer to support systems)
  • Pregnancy itself is a stressful experience – Stress-mitigating methods should be offered to all women
  • The results of this study should not be used to make pregnant women feel guilty about their choices to move during pregnancy

Learn More – Primary Sources:

Residence change during the first trimester of pregnancy and adverse birth outcomes (BMJ)

Opinion: Moving House During Pregnancy: Parental Choices and Relative Risks (BMJSRH)

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