Healthy Pregnancy Spacing

What is the "ideal" spacing of pregnancies?

Socially, there may be a wide range of opinions on the subject of how far apart your children should be. Theories abound as to the ideal spacing for the parents' sanity (condense the amount of time you're in diapers), the mental health of the children (will they get along if they're too close/too far apart?), and so on.

We know that many women "plan" to have their kids a certain number of years apart, others try to rely on natural family planning methods which sometimes lead to close pregnancies, and some women actively try to have several children within a limited time period.

Some couples decide to have or end up having several children close together, either because they had trouble conceiving at first, because they don't use a highly effective form of birth control, because they are reaching the end of their reproductive years, or because it is the norm in their social or religious community.

Often it is social/parenting reasons that dictate pregnancy spacing, and many women do not take into account the health impacts of pregnancy spacing. I believe it is my public health duty to tell you that the healthiest thing you can do is to wait at least 18 months to 2 years before conceiving the next baby.

Here's why:

Benefits of Spacing of 18+ months

It has been repeatedly demonstrated that adequate birth spacing reduces adverse events for both mothers and infants. Research on several populations found that the risk for adverse birth outcomes is lowest when the interpregnancy interval was 18-23 months. These studies controlled for maternal reproductive risk factors.

Adverse birth outcomes for the infant included low birth weight, preterm birth, and small for gestational age. There is also limited evidence that risk of autism increases.

Adverse outcomes for the mother include increased risk of uterine rupture in women attempting a vaginal birth after previous cesarean delivery and uteroplacental bleeding disorders (placental abruption, where the placenta detaches from the uterine wall, and placenta previa, where the placenta covers the cervical opening).

The benefits of waiting at least 2 years between births also extend beyond the pregnancy and birth outcomes. Closely spaced pregnancies often don't give the mothers body enough time to recover from the physical and metabolic stress of pregnancy and breastfeeding, which can deplete some nutrients. Furthermore (and this may not be relevant to your situation), for resource-poor families, two young children very close in age often leads to a time, energy, and resource disparity where one child suffers the consequences. There are some studies that show short interpregnancy interval length is associated with increased child mortality.

While you can tandem nurse an older and younger child, your milk does change during pregnancy and it may be best to finish you are prepared to possibly finish your breastfeeding relationship with your elder child before becoming pregnant.

If you had an adverse birth outcome with your previous birth (for example, low birth weight or premature baby), it is even more important to actively plan for your next baby, rather than leaving it to chance and potentially having a short birth interval. (The buzz word in public health is Interconception Care)


Consequences of (Too) Long Birth Intervals (5 years)

It is worth noting, however, that long birth intervals (~5 years) are associated with an increase with of preeclampsia (hypertension in pregnancy). Limited evidence shows an association with preterm birth and low birth weight, as well.

There are also hypotheses that waiting too long between pregnancies puts your body back into a state of a first time pregnancy, and the physiological changes caused by pregnancy that may help with pregnancy and labor may disappear.


I hope this helps you think about your pregnancy spacing and family planning! With all that in mind, I'll let you figure out where in that 2-5 year window is the best time for your family to deal with the practical demands of a growing family.


Resources:
http://www.ncbi.nlm.nih.gov/pubmed/15820365
http://www.physicianclassroom.org/uploads/1/8/9/5/1895381/effects_of_birth_spacing_on_birth_outcomes.pdf
http://www.sciencedirect.com/science/article/pii/S0002937806010064
http://www.mayoclinic.org/healthy-living/getting-pregnant/in-depth/family-planning/art-20044072
http://www.parents.com/pregnancy/considering-baby/another/best-time-to-have-2-or-3-babies/