White, Lois. Foundations Of Maternal & Pediatric Nursing, pages 10 and 128 (2004): "By the end of the 12th week, skeletal muscles begin involuntary movements....The newborn may cry and have muscular activity when cold, but there is no voluntary control of muscular activity."
Prechtl, Heinz. "Prenatal and Early Postnatal Development of Human Motor Behavior" in Handbook of brain and behaviour in human development, Kalverboer and Gramsbergen eds., pp. 415-418 (2001 Kluwer Academic Publishers): "The first movements to occur are sideward bendings of the head....At 9-10 weeks postmestrual age complex and generalized movements occur. These are the so-called general movements (Prechtl et al., 1979) and the startles. Both include the whole body, but the general movements are slower and have a complex sequence of involved body parts, while the startle is a quick, phasic movement of all limbs and trunk and neck."
Butterworth, George and Harris, Margaret. Principles of developmental psychology, page 48 (Psychology Press 1994): "stretch and yawn pattern at 10 weeks."
Valman HB, Pearson JF (enero de 1980). «What the fetus feels». Br Med J280 (6209): 233-4. PMC1600041. PMID7427089. doi:10.1136/bmj.280.6209.233. «Nine weeks after conception...fingers [bend] round an object in the palm of his hand. In response to a touch on the sole of his foot...hips and knees [bend] to move away from the touching object.»
Valman HB, Pearson JF (enero de 1980). «What the fetus feels». Br Med J280 (6209): 233-4. PMC1600041. PMID7427089. doi:10.1136/bmj.280.6209.233. «Nine weeks after conception...fingers [bend] round an object in the palm of his hand. In response to a touch on the sole of his foot...hips and knees [bend] to move away from the touching object.»
Becher, Julie-Claire. «Insights into Early Fetal Development». Archivado desde el original el 1 de junio de 2013. (Royal College of Physicians of Edinburgh and Royal College of Physicians and Surgeons of Glasgow October 2004): "Purposive movement depends on brain maturation. This begins at about 18 weeks' gestation and progressively replaces reflex movements, which disappear by about 8 months after birth....Reflexes are very different from purposeful voluntary movements which develop during the first year of life."
Becher, Julie-Claire. «Insights into Early Fetal Development». Archivado desde el original el 1 de junio de 2013. (Royal College of Physicians of Edinburgh and Royal College of Physicians and Surgeons of Glasgow October 2004): "Purposive movement depends on brain maturation. This begins at about 18 weeks' gestation and progressively replaces reflex movements, which disappear by about 8 months after birth....Reflexes are very different from purposeful voluntary movements which develop during the first year of life."
