Patient's question:
My baby just turned one month old, and I'm doing mixed feeding. Yesterday, the number of bowel movements increased from 1-2 times a day to 4 times. Today, my baby had one foamy bowel movement. Could you please advise a doctor on what to do if the baby has loose, smelly bowel movements? What could be the cause? I hope you can give me some suggestions and methods. Thank you in advance.Doctor's answer:
Baby's Stool and Health.I. Composition of Infant Stool
In normal infant stool, water accounts for 80% of the dry matter. The formed components consist of two-thirds food residue and one-third normal intestinal bacteria, along with trace amounts of mineral salts, bilirubin and its derivatives, and shed intestinal epithelial cells. The remaining one-third is bacteria, which might seem alarming, but these are actually beneficial bacteria such as Escherichia coli, Lactobacillus, Bifidobacterium, and Streptococcus faecalis. They break down food residue to produce vitamins for absorption and coexist with humans. Breastfed infants' stool primarily contains Lactobacillus and Bifidobacterium, while formula-fed infants' stool is mainly composed of Escherichia coli. Only the (black, viscous meconium) excreted within the first 2–3 days after birth does not contain bacteria.
II. Appearance of Normal Infant Stool
Normal infant stool is yellow or brown, soft and ribbon-like or paste-like. The consistency of stool is related to diet and frequency of defecation. Breastfed infants typically have 2–7 bowel movements daily, appearing yellow and greasy, sometimes containing curds. Formula-fed infants have 1–2 bowel movements daily, pale yellow and firmer. After introducing solid foods, such as green-leafy vegetables, green stool may occur. Eating animal liver or blood or taking iron supplements may result in black stool. Occasionally, undigested seeds, vegetable leaves, soybeans, or corn may be found in infant stool, but as long as the amount is small, this is normal.
III. Odor of Normal Infant Stool
Newborn meconium is odorless. Breastfed infants' stool has a slight sour odor, while formula-fed infants' stool is stronger but still less pungent than adult stool. After introducing solid foods, the bacteria in stool become similar to those in adults, and the odor intensifies. Under normal circumstances, intestinal bacteria break down food residue to produce indole and ammonia, which have a certain odor but are not too strong. If infant stool has an excessively strong odor or emits foul gas, it may indicate illness.
IV. pH of Infant Stool
During breastfeeding, infant stool contains more Lactobacillus and Bifidobacterium, which produce more acidic substances when breaking down stool residue, resulting in a pH (acidity/alkalinity) often below 5.5. In formula-fed infants, the bacteria differ from those in breastfed infants, making the stool neutral or slightly alkaline, with a pH typically between 6–8. To test stool pH, commercially available "precision test strips" can be used: dip one end of the strip into the stool for half a second, then compare it to the color chart provided with the strips to determine the pH. New parents might consider keeping a set at home for reference when suspecting infant diarrhea. If a child's diarrhea stool pH is below 6, it may be due to symptoms like cold exposure, improper diet, or other non-infectious diarrhea. In infectious diarrhea, the stool pH is often above 7.
V. Abnormal Stool and Infant Illness
Changes in stool frequency, appearance, and odor can reflect infant illness, especially gastrointestinal disorders.
Frequency Changes:
- Constipation is characterized by a sudden decrease in stool frequency and dry, hard stool.
- Diarrhea is marked by a sudden increase or decrease in stool frequency, along with changes in content.
Appearance Changes:
- Besides diarrhea, if the stool contains excessive mucus or blood and the infant cries during defecation, it may indicate bacterial dysentery or other infectious diarrhea caused by pathogens.
- If the stool resembles rice water, without abdominal pain, and the child rapidly develops dehydration, convulsions, or shock, it could be cholera.
- Watery stool may be due to bacterial or viral infectious diarrhea.
- Seawater-like stool suggests staphylococcal enteritis.
- Curd-like stool indicates fungal enteritis.
- If parasites are found in the stool, the diagnosis is obvious, but eggs are invisible to the naked eye. Microscopic examination of stool for eggs can diagnose parasitic diseases in the intestines, respiratory tract, or bile ducts.
Color Changes:
- White stool accompanied by jaundice and itching may indicate biliary obstruction.
- Green, watery stool is often due to cold exposure or improper solid food introduction, causing dietary diarrhea.
- Stool resembling dark red bean soup with a foul odor suggests hemorrhagic necrotizing enteritis.
- Jam-colored stool may indicate intussusception or amoebic dysentery.
- Black, tarry stool, after ruling out iron supplements or excessive consumption of animal liver, can indicate upper gastrointestinal bleeding.
- Fresh red blood in stool suggests rectal or anal bleeding.
Odor Changes:
- Excessive sour odor with foamy stool may result from excessive sugar or starch in the diet, leading to over-fermentation.
- Sudden, strong odor resembling rotten eggs may indicate a high-protein diet.
- Foul odor with a greasy feeling suggests excessive fat consumption.
- Foul, large-volume stool with weight loss in the child may indicate malabsorption syndrome.
- Extremely foul odor in infants is extremely rare and may be caused by intestinal cancer.