Birth and Development

Gestation: period of time that embryo/foetus spends in the uterus Parturition/birth: process of expelling the foetus from the Uterus Labour: series of events preceding parturition. During final 3 months of gestations uterus undergoes weak irregular contractions

STAGEs of labour

1st stage of labour (Dilation of the cervix) Lasts approx 8-9 hours (approx 4 every subsequent birth) Begin: Uterine contractions are occurring every 30 minutes. (Labour pains) Waves of muscle contractions (like peristalsis) from uterus to cervix, cause uterus to slightly shorten and pull back cervix causing it to dilate. End: Complete dilation (opening) of the cervix (10cm) Foetus head generally facing mothers left or right pelvic bone. Forms the birth canal: passage through which foetus will be expelled

2nd stage of Labour (Stage of expulsion) Lasts approx 20 mins – 2 hrs. Often marked by the breaking of the amniotic sac (release of amniotic fluid) Uterine contractions with voluntary abdominal contractions move foetus along birth canal, turning baby’s head to face mothers back. Slowly head will emerge and then turn to face sideways again. (allows shoulders to fit through more easily) Remainder of baby is expelled. (covered with vernix: waxy substance)

3rd stage of Labour (afterbirth) After baby is expelled, umbilical cord is clamped and cut. (remains attached to baby will dry up and fall off leaving ‘navel’ or ‘umbilicus) Approx 5 mins after delivery, placenta, remains of umbilical cord and other membranes are expelled. (afterbirth)

Changes at birth

Baby before birth: first breath of life due to shock / slap/ clamp umbilical cord (increase in CO2) Gas / nutrient / waste exchange occurs between placenta and endometrium Ductus venosus (liver bypass) Foramen ovale (hole in septum wall) Ductus arteriosus (lung bypass) Umbilical artery Umbilical vein

Baby after birth: decrease resistance in lungs: ductus arteriosus redundant (deteriorates) more flow in left atrium  pressure closes foramen ovale decreased blood flow through ductus venosus (deteriorates) to account for higher muscle activity / temp control / increase in O2 45 breaths / min (1st 2 weeks) 125 – 130 beats / min increased red blood cell count

Mother after birth: Puerperium (8weeks – uterus returns to normal size) due to contractions & gradual shrivelling Fluid discharge (blood, endometrium) lasts up to 3 – 6 weeks Mood changes (postnatal depression, 3rd day blues) Menstruation returns: Breastfeeding – in approx. 6 months No breastfeeding– within 10 weeks

Breastfeeding & Milk Production

The Breasts Until puberty, male / female breasts are very similar Approx 10-11, female nipples bulge (due to oestrogen / progesterone) Each breast = 15 – 25 sections (lobes) subdivided into lobules. Walls of each lobule consist of glandular alveoli (milk secreting region) All surrounded by fatty connective tissue Lobules open up into ‘milk space’ for storage (15 – 25) During the 1st weeks after birth, newborns environment must be kept as close to the Uterus as possible: Food & water  milk Warmth & comfort  cuddling arms / small soft bed

Lactation initiation & maintenance of milk secretion and delivery to infant Changes during Pregnancy lobes become larger & more complex nipple area darkens in colour oil secreting glands enlarge (prevents drying out of nipple) growth and development of breast Changes at Birth 1st secretion: Colostrum (watery, yellow / white – similar to normal milk but little fat & high levels of antibodies)

Milk Let-Down Reflex Baby suckles nipple msg sent to brain via nerves brain tells pituitary gland to secrete Oxytocin & Prolactin Oxytocin triggers contraction of muscles around lobules / Prolactin triggers milk production Milk is ejected into ducts Up to 1.5 L of milk / day may be produced Needs Vit D, Calcium, phosphate

Development: Infancy to adolescence

Infancy Physical Development: In 1st year body length increases by 1/3 and weight triples. (71-74cm, 9kg) Head/leg ratio changes dramatically with legs growing much faster than the head. By 15, body proportions are very similar to adulthood. Social Development: Socialisation: ability to behave in a manner that is accepted and approved by other people.

Pattern of development Infancy Motor Development: The ability to control movement of a particular part of the body Pattern of development Order of development Cephalocaudal Development from head to foot Proximodistal Development outwards. (forearm movements learnt first, finger movements last) Gross to Specific Development of larger muscle movements before finer muscle movements

Adolescence Transition between childhood and adulthood (starts approx 11+) Puberty: time during which an adolescent develops sexual maturity (ability to reproduce)   Physical Development: Adolescent growth spurt: rapid increase in height and weight (males: 13-16 , females: 11-14) Growth in height, weight, heart & lungs etc. Reproductive development: development of primary and secondary sexual characteristics. Social Development: Transition to independence