Talk:Birth

From Embryology

Are babies getting bigger? An analysis of birthweight trends in New South Wales, 1990-2005

Hadfield RM, Lain SJ, Simpson JM, Ford JB, Raynes-Greenow CH, Morris JM, Roberts CL. Med J Aust. 2009 Mar 16;190(6):312-5. PMID: 19296812

OBJECTIVE: To determine whether the proportion of babies born large for gestational age (LGA) in New South Wales has increased, and to identify possible reasons for any increase.

DESIGN AND SETTING: Population-based study using data obtained from the NSW Midwives Data Collection, a legislated surveillance system of all births in NSW.

PARTICIPANTS: All 1 273 924 live-born singletons delivered at term (> or = 37 complete weeks' gestation) in NSW from 1990 to 2005.

MAIN OUTCOME MEASURES: LGA, defined as > 90th centile for sex and gestational age using 1991-1994 Australian centile charts; maternal factors associated with LGA were assessed using logistic regression.

RESULTS: The proportion of babies born LGA increased from 9.2% to 10.8% (18% increase) for male infants and from 9.1% to 11.0% (21% increase) for female infants. The mean birthweight increased by 23 g for boys and 25 g for girls over the study period. Increasing maternal age, higher rates of gestational diabetes and a decline in smoking contributed significantly to these increases, but did not fully explain them.

CONCLUSIONS: There is an increasing trend in the proportion of babies born LGA, which is only partly attributable to decreasing maternal smoking, increasing maternal age and increasing gestational diabetes.

eMJA

Invited review: Clearance of lung liquid during the perinatal period

J Appl Physiol. 2002 Oct;93(4):1542-8.

Barker PM, Olver RE.

Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina 27599-7220, USA. pbarker@med.unc.edu

Abstract At birth, the distal lung epithelium undergoes a profound phenotypic switch from secretion to absorption in the course of adaptation to air breathing. In this review, we describe the developmental regulation of key membrane transport proteins and the way in which epinephrine, oxygen, glucocorticoids, and thyroid hormones interact to bring about this crucial change in function. Evidence from molecular, transgenic, cell culture, and whole lung studies is presented, and the clinical consequences of the failure of the physiological mechanisms that underlie perinatal lung liquid absorption are discussed.

PMID: 12235057

http://www.ncbi.nlm.nih.gov/pubmed/12235057

http://jap.physiology.org/cgi/content/full/93/4/1542

Birth lecture

Newborn Homoeostasis

Brown adipose tissue

Newborn has to establish new functioning systems in a balanced and regulated manner (homoeostasis).

  • lung function
  • circulatory changes
  • thermoregulation
  • endocrine function
  • nutrition
  • gastrointestinal tract function
  • waste
  • kidney function

Glucocorticoids - have an important role in the preparation for birth, including involvement in lung and cardiac development, and the maturation of enzymes in a variety of pathways.

Respiration

Neonatal rib orientation
  • Lungs at birth collapsed and fluid-filled - replaced with air by powerful inspiratory movement and absorption through the alveoli
  • Lung epithelia has to rapidly change from its prenatal secretory function to that of fluid absorbtion.
    • initiated by a late fetal change in alveolar epithelial cell (AEC) chloride and fluid secretion to sodium and fluid absorption.
    • absorption requires sodium-potassium ATPase (Na-K-ATPase) together with apical sodium entry mechanisms (Epithelial Sodium Channels, ENaC)
    • Fetal thyroid hormone is thought to have a hormonal role in this developmental switch
  • These changes and pressure also lead to the pulmonary sytem becoming activated and changes in the circulatory shunting that existed before birth.
  • During the late fetal period regular fetal breathing movements (FBM) also occur preparing both the skeletomuscular sysyem and lungs mechanically for respiration.
  • Respiratory Rate is higher than adult (30 breaths/minute).
  • Rib Orientation - Infant rib is virtually horizontal, allowing diaphragmatic breathing only. Adult rib orientation is oblique (both anterior and lateral views), allows for pump-handle and bucket handle types of inspiration.

Postnatal Development - Respiratory

Cardiovascular

  • Umbilical Vasculature - The umbilical blood vessel cavity is lost postnatally over the course of weeks to months after birth. The adult anatomical remnant of the umbilical vein between the umbilicus and liver is the ligamentum teres.
  • Foramen Ovale - two separate forms of foramen ovale closure; functional and structural. Functional closure begins at the first breath and is rapid. Structural (anatomical) closure is much slower and generally occurs before the end of the first year.
  • Ductus Arteriosus - a direct connection between the pulmonary trunk and the dorsal aorta. Postnatal closure occurs initially by by smooth muscle contraction and begins at the first breath and is rapid, completed within the first day (about 15 hr after birth). Anatomical closure is much slower occuring by 2–3 weeks after birth (33% of infants), by 2 months (90% of infants) and by 1 year (99% of infants). The adult anatomical remnant of the ductus arteriosus is the ligamentum arteriosum.
  • Ductus Venosus - connects portal and umbilical blood to the inferior vena cava. Functional closure occurs postnatally within hours. Structural closure commences days after birth and completes by 18 to 20 days. The adult anatomical remnant of the ductus venosus is the ligamentum venosum (a dorsal fissure on the liver).

Links

Vaginal delivery of breech presentation.

Kotaska A, Menticoglou S, Gagnon R, Farine D, Basso M, Bos H, Delisle MF, Grabowska K, Hudon L, Mundle W, Murphy-Kaulbeck L, Ouellet A, Pressey T, Roggensack A; Maternal Fetal Medicine Committee; Society of Obstetricians and Gynaecologists of Canada. J Obstet Gynaecol Can. 2009 Jun;31(6):557-66, 567-78. English, French. PMID: 19646324


Birth Weight Conversion

  • Extremely Low Birth Weight (ELBW)
    • Less than 500 grams
    • 500 – 999 grams
  • Very Low Birth Weight (VLBW)
    • 1,000 – 1,499 grams
  • Low Birth Weight (LBW)
    • 1,500–1,999 grams
    • 2,000–2,499 grams
  • Normal Birth Weight
    • 2,500–2,999 grams
    • 3,000–3,499 grams
    • 3,500–3,999 grams
  • High Birth Weight (macrosomia)
    • 4,000–4,499 grams
    • 4,500–4,999 grams
    • 5,000 grams or more


Less than 500 grams=1 lb 1 oz or less

500–999 grams = 1lb2oz–2lb3oz

1,000–1,499 grams = 2 lb 4 oz–3 lb 4 oz

1,500–1,999 grams = 3 lb 5 oz–4 lb 6 oz

2,000–2,499 grams = 4 lb 7 oz–5 lb 8 oz

2,500–2,999 grams = 5 lb 9 oz–6 lb 9 oz

3,000–3,499 grams = 6 lb 10 oz–7 lb 11 oz

3,500–3,999 grams = 7 lb 12 oz–8 lb 13 oz

4,000–4,499 grams = 8 lb 14 oz–9 lb 14 oz

4,500–4,999 grams = 9 lb 15 oz–11 lb 0 oz

5,000 grams or more = 11 lb 1 oz or more

Macrosomia

  • large size of parents (especially the mother)
  • multiparity diabetes in the mother
  • prolonged gestation
  • older maternal age
  • male infants
  • previous delivery of a high birthweight infant

Gestation

from same USA report

The primary measure used to determine the gestational age of the newborn is the interval between the first day of the mother’s last normal menstrual period (LMP) and the date of birth. It is subject to error for several reasons, including imperfect maternal recall or misidentification of the LMP because of post conception bleeding, delayed ovulation, or intervening early miscarriage.

The U.S. Standard Certificate of Live Birth includes an item, ‘‘clinical/obstetric estimate of gestation,’’ that was compared with length of gestation computed from the date the last normal menstrual period (LMP) began when the latter appeared to be inconsistent with birth- weight.


USA Births: Final Data for 2006

  • In 2006, the number of births and birth and fertility rates increased for nearly all age groups, live-birth orders, race, and Hispanic origin groups and reporting areas. In some cases, rates rose to levels not seen in three or more decades.
  • A total of 4,265,555 births were registered in the United States in 2006, 3 percent higher than in 2005. This is the largest single-year increase in births since 1989 and the largest number since 1961. Births increased for all race and Hispanic origin groups between 2005 and 2006.
  • The crude birth rate for the U.S. was 14.2 live births per 1,000 persons in 2006, up slightly from 2005. The general fertility rate was 68.5 births per 1,000 women aged 15–44 years, an increase of 3 percent over 2005 and the highest rate reported since 1991. Fertility rates for nearly all race and Hispanic origin groups increased.
  • Birth rates increased for women of most age groups between 2005 and 2006. The only exceptions were the youngest mothers (under age 15 years) for whom the rate declined slightly, and mothers aged 45–49 years, for whom the birth rate was unchanged.
  • The birth rate for teenagers 15–19 years increased 3 percent in 2006, interrupting the 14-year period of continuous decline from 1991 through 2005. Only the rate for the youngest adolescents declined in 2006, to 0.6 per 1,000 aged 10–14 years. Rates for teenagers 15–17 and 18–19 years rose 3 to 4 percent each. These increases follow declines of 45 and 26 percent, respectively, in the rates between 1991 and 2005. Between 2005 and 2006, birth rates increased 3 to 5 percent each for non-Hispanic white, non- Hispanic black, and American Indian or Alaska Native teenagers and 2 percent for Hispanic teenagers. The rate for Asian or Pacific Islander teenagers was unchanged. Teenage birth rates increased significantly between 2005 and 2006 in 26 states, representing nearly every region of the country.
  • The first birth rate for women aged 15–44 years increased 3 percent to 27.4 births per 1,000 women. First birth rates increased for nearly all age groups.
  • Labor was induced for 22.5 percent of births in 2006, a slight increase over 2005, and double the rate for 1990. Induction rates are up substantially for all gestational ages, including preterm births, since 1990.
  • The cesarean delivery rate rose 3 percent to 31.1 percent of all births, another record high. The cesarean rate has climbed 50 per­ cent since the 1996 low. Rates for primary cesareans were up and vaginal births after previous cesarean were down for both revised and unrevised reporting areas. Cesarean rates have risen at all gestational ages over the last decade.
  • The preterm birth rate rose again in 2006 to 12.8 percent of all births. The percentage of infants delivered at less than 37 com­ pleted weeks of gestation has climbed 20 percent since 1990. Most of this rise is attributable to the increases in late preterm births (34–36 weeks), up 25 percent since 1990. Preterm birth rates rose slightly for Hispanic infants, but were unchanged among non-Hispanic white and non-Hispanic black infants. The singleton preterm rate also increased in 2006, to 11.1 percent. This rate has climbed 14 percent since 1990.
  • The low birthweight (LBW) rate also continued to rise, climbing to 8.3 percent in 2006, the highest level in four decades. The percentage of infants born at less than 2,500 grams has risen 19 percent since 1990. All of the rise for 2005–2006 was among moderately LBW (1,500–2,499 grams) infants. LBW rates rose slightly for Hispanic infants, but were unchanged for non-Hispanic white and non-Hispanic black infants. The LBW rate for infants born in single deliveries also increased in 2006; singleton LBW has risen 10 percent since 1990.
  • The rapid rise in multiple birth rates over the last several decades may have ended. The 2006 twin birth rate (32.1 twins per 1,000 births) remained essentially unchanged from 2005. The twin birth rate climbed 70 percent between 1980 and 2004. The triplet plus/+ birth rate declined 5 percent for 2005–2006, to 153.3 per 100,000 total births. This rate soared more than 400 percent between 1980 and 1998, but is down 21 percent since then.


Martin JA, Hamilton BE, Sutton PD, Ventura SJ, et al. Births: Final data for 2006. National vital statistics reports; vol 57 no 7. Hyattsville, MD: National Center for Health Statistics. 2009. National vital statistics reports; vol 57 no 7 PDF

Copyright information - All material appearing in this report is in the public domain and may be reproduced or copied without permission; citation as to source, however, is appreciated.

data file download

VitalStats - is a A new data access and analysis tool VitalStats

National Vital Statistics Reports [1]

VitalStats Perinatal Mortality (USA)

http://www.cdc.gov/nchs/data_access/vitalstats/VitalStats_Perinatal_Mortality.htm

"Notice of Error in the 2003 and 2004 Fetal Death Data Files and Reports, and Instructions for Correcting the Data File Error

Due to a programming error, the Tabulation Flag variable located in position 9 is incorrect in the 2003 and 2004 fetal death data files. This variable identifies fetal deaths of stated or presumed period of gestation of either <20 weeks, or 20 weeks or more. Most tabulations and reports of fetal death data include only fetal deaths of 20 weeks of gestation or more. Due to this error, some fetal death records with not stated gestational ages that should have been included in the 20 weeks or more group were erroneously assigned to the <20 week group. This led to a slight underestimate of fetal mortality rates published in the National Vital Statistics Reports: Fetal and Perinatal Mortality, United States, 2003 and Fetal and Perinatal Mortality, United States, 2004. The documentation tables published in the Fetal Death User’s Guides for 2003 and 2004 are also incorrect. Tables 1 and 2 below show the effect of correcting this error on fetal and perinatal mortality rates. It should be emphasized that although the corrected rates are a bit different from those originally published, they are not statistically different in that the statements about statistical significance or lack thereof made in the fetal and perinatal reports for 2003-2005 did not change. In other words, the US fetal mortality rate did not decline significantly from 2002-03, 2003-04, 2004-05, or 2003-05. There was a significant decline in the fetal mortality rate from 2002-04 and 2002-05. In the vast majority of the states, the corrected numbers differed from the originally reported numbers by less than 1.0 percent in each year (Tables 2 and 3)."

USA Weight Gain in Pregnancy

In 1990, the Institute of Medicine (IOM) issued recommendations for gestational weight gain (43). These guidelines are based on the mother’s body mass index (BMI), which takes into account both the mother’s height and weight.

A recent workshop held by the IOM and National Academy of Sciences developed a research agenda empha­ sizing the need to make specific recommendations for subgroups such as: adolescent mothers, mothers in diverse racial and ethnic groups, and mothers carrying twins or higher order multiples (44).

2006 Data

  • 13 percent of all mothers gained less than 16 pounds (considered inadequate for most women)
  • 21 percent had weight gains of more than 40 pounds (considered excessive for all women).
  • approximately one-third of all mothers had weight gains outside of the guidelines, regardless of their height.

reference

Maternal age and diabetes risk

  • diabetes rate for mothers 40 years of age and over was 94.3 per 1,000 (2006)
    • 6 times higher than that for mothers under 20 years of age (13.3 per 1,000).
  • Diabetes rates also differ by maternal race and ethnicity
    • highest for API mothers (7.1 percent)
    • AIAN (6.4 percent)
    • Hispanic (4.3percent) Hispanic subgroups, percent­ ages ranged from 4.0 for Cuban to 4.9 for Puerto Rican mothers.
    • non-Hispanic white (4.0percent)
    • non-Hispanic black mothers (3.7 percent)

Smoking During Pregnancy

  • overall smoking rate was 13.2 percent
    • For the 17 states for which revised information on tobacco use is available for 2006