At least one year is the ideal pregnancy spacing time for the health of mother and baby

  

One to one and a half year is the ideal spacing time between pregnancies according to researchers from the University of British Columbia (B.C.) and the Harvard T.H. Chan School of Public Health.

The study found an increased risk of premature births, maternal morbidity and mortality, and adverse neonatal outcome following an interpregnancy interval of fewer than 12 months in women of all ages. However, women who were 35 or more were at increased risks of maternal mortality or severe morbidity, while women aged 20 to 34 years were at increased risk of preterm labor and adverse fetal and infant outcomes.

In this large cohort study published online October 29 in JAMA Internal Medicine, the researchers looked at data from 148,544 pregnancies in B.C. to examine the relationship between interpregnancy interval and adverse pregnancy. The data was gathered from billing codes, hospitalization data, birth records, prescription data for infertility information, and census records for a period of 10 years (2004 to 2014).

The study is the most extensive and in-depth evaluation of the relationship between pregnancy spacing and maternal age. Currently, it is unknown whether older women face the same risk as younger women because of a shorter interpregnancy interval.

Women aged 35 and more who conceived within six months of a previous birth, faced 1.2 percent risk (12 cases per 1,000 pregnancies) of maternal mortality or severe morbidity (mechanical ventilation, blood transfusion >3 U, intensive care unit admission, and organ failure). Keeping an interpregnancy interval of 18 months, however, reduced the risk to 0.5 percent (five cases per 1,000 pregnancies).

For younger women, who conceived within six months of last childbirth, the researchers found an 8.5 percent risk (85 cases per 1,000 pregnancies) of spontaneous preterm birth, but the risk dropped to 3.7 percent (37 cases per 1,000 pregnancies) if the women waited 18 months before the next conception. 

Among older women, the risk of spontaneous preterm labor was about six percent (60 cases per 1,000 pregnancies) at the six-month interval, compared to 3.4 percent (34 cases per 1,000 pregnancies) at the 18-month interval.

“Our study found increased risks to both mother and infant when pregnancies are closely spaced, including for women older than 35,” said the study’s lead author Laura Schummers in a University of British Columbia news release. Dr. Schummers is a postdoctoral fellow in the UBC department of family practice who carried out the study as part of her dissertation at the Harvard T.H. Chan School of Public Health. “The findings for older women are particularly important, as older women tend to more closely space their pregnancies and often do so intentionally,” she further added. 

Senior author Dr. Wendy Norman, associate professor in the UBC department of family practice, said these findings of a shorter optimal interval are encouraging for women over 35 who are planning their families.

“Older mothers for the first time have excellent evidence to guide the spacing of their children,” said Norman. “Achieving that optimal one-year interval should be doable for many women and is clearly worthwhile to reduce complication risks.”

JAMA Internal Medicine Full Text

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