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A newborn’s first bowel movement is called meconium. It is a thick, sticky, black to dark green substance. It begins to be formed inside the fetus’ intestines at about the 12-16th week of gestation. It is made up of amniotic fluid, lanugo (hair growing on the fetus/skin) and cells shed from the fetus’ skin and intestinal tract. Normally meconium is not excreted until after birth, and can be used to test for drugs. It can give information on maternal drug use from about 12 weeks through the end of the pregnancy.

Once the newborn starts to eat, the stool changes and becomes more seedy and yellow. The yellow comes from the pigment bilirubin, which is an end product of the recycling of the hemoglobin molecule in red blood cells.

Breast fed babies have smaller, softer stools that formula fed babies, as almost all of the breast milk is absorbed by the intestine. Formula fed babies have larger, firmer stools as more of the formula is not absorbed and passes through.

Stools can come in many colors – brown, green, orange are usual, with the bulk of the colors caused by the byproducts of the bacteria which normally inhabit the bowel. Food colors can also affect the color of the bowels.

There are some worrisome colors – black, red and white.

Red is usually caused by bleeding somewhere near the end of the intestine. Anal fissures are a common cause. These are small tears which can often be seen around the anus, often caused by large bowel movements. These usually heal spontaneously. Rectal polyps can also cause bright red blood and usually require a minor surgical procedure for removal.

Black stools usually imply intestinal bleeding from higher levels of the intestine.

White (acholic) stools often indicate liver problems.

Babies with persistent red, black or white stools should be seen by their physician promptly.

Infant stools should be soft to mushy rather than hard.  Hard stools can be difficult and painful to pass and can lead to toileting difficulties. Toddlers who drink an excessive amount of milk – greater than 26 ounces a day – will often eat fewer solids and can become quite constipated. Diet changes can often help. Increasing fiber (leafy vegetables) can help to soften stools, as can the “P” fruits – peaches, pears, plums, prunes and apricots. Oatmeal can also help.

When stools are too soft – near liquid, diet can also help. Apples, bananas and rice cereal can help to thicken stools.

Stools can smell pretty bad – as my dad used to say, “You’re not feeding them roses!”

This blog post was re-posted with permission by Dr. Lawrence Wasser. It originally appeared on his personal blog, Parenting Infants and Toddlers.

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Lawrence Wasser, M.D.

Dr. Lawrence Wasser is currently a pediatrician with UofL Physicians -- Pediatrics and associate professor of Pediatrics at the University of Louisville School of Medicine. Dr. Wasser was born in the Bronx, N.Y. and grew up in Linden, New Jersey. He received his b.s. in engineering and applied science from Yale University in 1970, and his M.D. in 1974 from Johns Hopkins University School of Medicine. He then completed a three year residency in pediatrics at Children’s Hospital in Boston, followed by a fellowship in behavioral and developmental pediatrics at the Child Development Unit at Harvard University School of Medicine, under the leadership of Dr. T. Berry Brazelton. Dr Wasser then joined a private practice in Louisville, where he worked in primary care for 27 years. He then joined the full-time faculty at the University of Louisville School of Medicine in the general pediatrics division at the UCHS practice on Broadway. In 2010, he moved to his current position as the director of the Newborn Nursery at the University of Louisville Hospital. For many years, Dr. Wasser has been giving parenting workshops both lo cally and nationally, helping parents survive the challenges of raising toddlers. He is the author of his own blog, Parenting Infants and Toddlers, http://toddlerdoc.blogspot.com/.

All posts by Lawrence Wasser, M.D.
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