Periods of Prenatal Development Period and Length Key Events Zygote (2 weeks) Fertilization Implantation Start of placenta Embryo (6 weeks) Groundwork laid for all body structures and internal organs Fetus (30 weeks) “Growth and finishing” phase

Conception and Implantation Figure 3.1 Female reproductive organs, showing fertilization, early cell duplication, and implantation. Figure 3.1 (From Before We Are Born, 6th ed., by K.L. Moore & T.V.N. Persaud, p. 87. Copyright © 2003, reprinted with permission from Elsevier, Inc.)

Period of the Fetus Third month: Second trimester: Third trimester: organs, muscles, and nervous system start to become organized and connected lungs begin to expand and contract Second trimester: many organs are well-developed by 20 weeks most of the brain’s neurons are in place Third trimester: age of viability: 22–26 weeks fetus takes on beginnings of personality

Sensitive Periods in Prenatal Development Figure 3.2 (Adapted from Before We Are Born, 7th ed., by K.L. Moore & T.V.N. Persaud, p. 313. Copyright © 2008, reprinted with permission from Elsevier, Inc.) Figure 3.2 Sensitive periods in prenatal development

Teratogens Harm done by teratogens is affected by: dose heredity age other negative influences © Phil McDonald/Shutterstock 10

Teratogenic Substances Drugs: prescription nonprescription illegal Tobacco Alcohol Radiation Environmental pollution Infectious disease © Minerva Studio/Fotolia

Other Maternal Factors in Prenatal Development Nutrition Emotional stress Rh factor incompatibility Age Lack of prenatal health care © Dmitry Melnikov/Shutterstock

Importance of Prenatal Care Monitor general health: weight gain capacity of uterus and cervix to support fetus growth of the fetus Treat complications: diabetes preeclampsia © Poznyakov/Shutterstock

Stages of Childbirth Dilation and effacement of the cervix Delivery of the baby Delivery of the placenta © Monkey Business Images/Shutterstock

Stages of Labor Figure 3.4 A Normal Birth Figure 3.4

The Baby’s Adaptation to Labor and Delivery High levels of stress hormones help baby withstand oxygen deprivation prepare baby to breathe arouse infant into alertness © nattanan726/Shutterstock

The Apgar Scale Table 3.2 (Source: Apgar, 1953.) Table 3.2 The Apgar Scale

Natural, or Prepared, Childbirth Classes Relaxation and breathing techniques Labor coach: friend, relative, or trained doula © KAMONRAT/Shutterstock

Birth Complications Anoxia (oxygen deprivation) Breech position © giorgiomtb/Shutterstock

Medical Interventions in Childbirth Fetal monitoring Labor and delivery medication analgesics anesthetics Cesarean delivery © ARZTSAMUI/Shutterstock

Preterm and Small-for-Date Infants Born several weeks or more before their due date Weight may be appropriate for length of pregnancy Small-for-Date May be either preterm or full-term Below expected weight for length of pregnancy

Interventions for Preterm Infants Temperature-controlled isolette Special stimulation: gentle rocking visual or auditory stimulation touch, such as skin-to-skin kangaroo care Parent training in infant caregiving © Damon Yancy/Shutterstock

Infant Mortality in Thirty Nations Figure 3.5 Infant mortality in thirty nations Figure 3.5 (Adapted from U.S. Census Bureau, 2012.)

Newborn Reflexes Rooting Sucking Moro Stepping © philipus/Fotalia

Infant States of Arousal Rapid-eye-movement (REM) sleep Non-rapid-eye-movement (NREM) sleep Drowsiness Quiet alertness Waking activity and crying © Vasilyev Alexandr/Shutterstock

Soothing a Crying Baby Hold on shoulder, rock or walk Swaddle Offer pacifier Massage baby’s body Talk softly or play rhythmic sounds Combine methods © Jo Tunney/Shutterstock

Newborn Sense of Touch Sensitive to touch around mouth on palms and soles of feet Use touch to investigate their world Severe pain overwhelms nervous system with stress hormones can be relieved with local anesthesia, sugar solution, or physical touch © Eleonora_os/Shutterstock

Newborn Senses of Taste and Smell Infants have a preference for sweet tastes at birth can readily learn to like new tastes have odor preferences at birth can locate odors and identify mother by smell from birth

Newborn Sense of Hearing can hear a wide variety of sounds prefer complex sounds to pure tones can distinguish between a variety of sound patterns when only a few days old listen longer to human speech than to nonspeech sounds can detect the sounds of any human language

Newborn Sense of Vision Least developed sense at birth Limited visual acuity Actively explore environment: scan for interesting sights track moving objects Not yet good at discriminating colors © Saylakham/Shutterstock

New Family Adjustment Hormones that facilitate caregiving: oxytocin prolactin estrogens Hormonal effects may depend on experience Challenges of early weeks: new roles changed schedule © ClickPop/Shutterstock