nutr chapter 16

• Gestation length and birth weight

  Greatly determine an infant's chance of survival
• Full-term gestation period


  39 or 40 weeks
• Preterm


  Born before 37 weeks
• Preterm infants may have medical problems and low birth weight (weighing less than 5.5 lb)
• Preterm birth is linked to suboptimal maternal nutrient and calorie intake
• Small for gestational age

  Infants that weigh less than expected for their gestational age
• Prenatal Development Stages

  1. Conception

  2. Zygotic

  3. Embryonic

  4. Fetal
• Gestation begins after conception
• Zygote forms and attaches itself to uterine lining
• Embryo is the next stage, 2 weeks after conception
• Embryo


  • 3 thin layers are formed: Endoderm (develops into digestive system, liver, and pancreas), Mesoderm (develops into skeleton, muscles, heart, and blood vessels), Ectoderm (develops into skin, nervous system, and sensory organs)
• Fetus

  Developing offspring from week 9 to birth
• Most rapid growth occurs in the fetal stage
• Length increases 20 times, averaging 20 to 22 inches
• Weight increases 3500 times, averaging 7 to 8 pounds
• Body fat increases to 16%
• Issues with premature infants

  • Difficulty regulating body temperature
  • Risk of nutrient deficiencies
• Trimesters


  Pregnancy is divided into three
• Developmental processes occur on schedule
• Critical periods for cells to develop into particular structures mostly occur during first trimester
• Nutrient deficiencies or excesses, pathogens, trauma, radiation, tobacco smoke, and toxins interfere with normal development
• Potential effects of calorie deficiency

  • Growth retardation
  • Low birth weight
• Potential effects of calorie excess

  • High birth weight
  • Complications during labor and delivery
• Potential effects of protein deficiency

  • Reduced head circumference
  • Fewer cells than normal, impact particularly severe in the brain
• If high protein consumption is coupled with low carbohydrate intake, may lower glucose availability and restrict energy available to the fetus
• Potential effects of vitamin C deficiency

  • Premature birth
  • Sudden drop in vitamin C after birth may cause vitamin C deficiency symptoms
• Potential effects of folate deficiency

  • Spontaneous abortion
  • Fluid accumulation in the skull, leading to brain damage
  • Growth retardation
  • Premature birth
  • Neural tube defects
• Folate may inhibit maternal absorption of other nutrients and hinders diagnosis of maternal vitamin B-12 deficiency
• Potential effects of vitamin A deficiency

  • Premature birth
  • Eye abnormalities and impaired vision
• Potential effects of vitamin A excess

  • Maternal death
  • Birth defects that affect the nervous and cardiovascular systems
  • Facial deformities
• Potential effects of vitamin D deficiency

  • Low birth weight
  • Rickets
  • Lack of enamel on teeth
• Potential effects of vitamin D excess

  • Calcification of soft tissues, such as the kidneys
  • Mental retardation
  • Growth retardation
• Potential effects of calcium deficiency

  • Decreased bone density
• Calcium excess may hinder maternal absorption of minerals, such as iron and zinc
• Potential effects of iron deficiency

  • Low birth weight
  • Premature birth
  • Increased risk of fetal or infant death
• Iron excess may hinder maternal absorption of minerals, such as zinc and calcium
• Potential effects of iodine deficiency

  • Cretinism (mental and physical growth retardation)
  • Thyroid disorders
• Potential effects of zinc deficiency

  • Nervous system malformations
  • Growth retardation
  • Birth defects that affect the brain and bones
• Zinc excess may hinder maternal absorption of minerals, such as copper and iron
• Placenta


  Delivers nourishment to developing embryo and fetus