When is scientifically the best time to have your second child?

When is scientifically the best time to have your second?
byu/EFNich inScienceBasedParenting

Inspired by the above reddit post and the different views on the topic of picking the best interpregnancy period,  I created the below timeline based on scientific proof of the best time to have your second baby. It adds value to the reddit post by visually summarising all the info from the reference links and also spotting some contradictory outcomes.

Insights

The best period to have your second baby is between 18 and 24 months after delivering the first baby.

STUDY 1

Conceiving less than 6 months after delivery was associated with an increased risk of adverse outcomes for mom and baby but that waiting 24 months may not be necessary for high-income countries.

STUDY 2

Children conceived less than 18 months after their mother’s previous birth or children conceived 60 or more months after their mother’s previous birth were more likely to have ASD when compared to children conceived between 18 to 59 months after their mother’s previous birth.

STUDY 3

To reduce the risk of pregnancy complications and other health problems, research suggests waiting 18 to 24 months but less than five years after a live birth before attempting your next pregnancy.

STUDY 4

For children conceived less than 12 months or more than 72 months after the birth of an older sibling, the risk of autism was two to three fold higher than for those conceived 36 months to 47 months later.

STUDY 5

Biggest risk recorded for children conceived less than 12 month after the birth of an older sibling.

STUDY 6

• The risk for preterm birth was high if the interpregnancy interval was <6 months.
• The risk for preterm birth declined as the interval increased and reached the lowest level when the interpregnancy interval was between 12 and 23 months.
• For interpregnancy intervals of ≥24 months, the risk for preterm birth gradually increased.
• The risk for preterm birth was high if the interpregnancy interval was ≥120 months.

STUDY 7

An increased risk of preterm birth for children born after IPIs of less than 13 months and >60 months relative to the reference category of 19–24 months.

STUDY 8

• “We compared approximately 3 million births from 1.2 million women with at least three children and discovered the risk of adverse birth outcomes after an interpregnancy interval of less than six months was no greater than for those born after an 18-23 month interval,” Dr Tessema said.
• “Given that the current recommendations on birth spacing is for a waiting time of at least 18 months to two years after live births, our findings are reassuring for families who conceive sooner than this.
• “However, we found siblings born after a greater than 60-month interval had an increased risk of adverse birth outcomes.”

STUDY 9

To reduce the risk of pregnancy complications and other health problems, research suggests waiting 18 to 24 months but less than five years after a live birth before attempting your next pregnancy. Balancing concerns about infertility, people older than 35 might consider waiting 12 months before becoming pregnant again.

STUDY 10

Intervals shorter than 36 months and longer than 60 months are associated with an elevated risk of infant death and other adverse outcomes.

STUDY 11

Compared to individuals whose first two children were born at most 18 months apart, individuals whose children were more widely spaced had a lower divorce risk.

References

• STUDY 1: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0255000
• STUDY 2: https://www.cdc.gov/ncbddd/autism/features/time-between-births.html
• STUDY 3: https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/in-depth/family-planning/art-20044072
• STUDY 4: https://time.com/4033506/autism-risk-siblings/
• STUDY 5:
  • https://researchonline.lshtm.ac.uk/id/eprint/4663143/7/Schummers_etal_2021_Short-interpregnancy-interval-and-pregnancy.pdf
  • https://www.dovepress.com/association-of-short-and-long-interpregnancy-intervals-with-adverse-bi-peer-reviewed-fulltext-article-IJGM
• STUDY 6: https://www.michigan.gov/-/media/Project/Websites/mdhhs/Folder4/Folder15/Folder3/Folder115/Folder2/Folder215/Folder1/Folder315/200804IPI_PTB_LBW_SGA_2008-2018.pdf?rev=e978a7ae96db445ebb0a4cf6d31ea8f9
• STUDY 7: https://www.tandfonline.com/doi/full/10.1080/00324728.2020.1714701
• STUDY 8: https://www.sciencedaily.com/releases/2021/07/210719143421.htm
• STUDY 9: https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/in-depth/family-planning/art-20044072
• STUDY 10: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6667399/
• STUDY 11: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993964/

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