SOURCES: JA Martin, BE Hamilton, SJ Ventura, MJK Osterman, S Kirmeyer, TJ Mathews, EC Wilson, “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011. JA Martin, BE Hamilton, PD Sutton, S Ventura, TJ Matthews, MJK Osterman, “Births: Final Data for 2008,” National Vital Statistics Reports 59(1), December 2010. Book of Odds estimate based on Centers for Disease Control and Prevention, Compressed Mortality File, 1979–2005, http://wonder.cdc.gov/mortsql.html. Book of Odds estimate based on Centers for Disease Control and Prevention, American Society for Reproductive Medicine, Society for Assisted Reproductive Technology, 2008 Assisted Reproductive Technology Success Rates: National Summary and Fertility Clinic Reports, Atlanta: US Department of Health and Human Services, 2010.
Fertility Treatments
The odds a female 15–44 has been treated for infertility are 1 in 8.3, and 1 in 90.9 women has used artificial insemination. The odds a woman will be treated for infertility to conceive increases with age. For women 40–44, 1 in 49.5 has used artificial insemination.
But the effectiveness of fertility treatments declines as a woman ages. For in vitro fertilization using a woman’s own, unfrozen eggs, the success rates are:
Before Age 35:
48% pregnancy success, 41% live birth success
Age 35–37:
38% pregnancy success, 31% live birth success
Age 38–40:
30% pregnancy success, 22% live birth success
Age 41–42:
20% pregnancy success, 12% live birth success
Age 43–44:
11% pregnancy success, 5% live birth success
SOURCES: Book of Odds estimate based on Centers for Disease Control and Prevention, National Survey of Family Growth 2006–2008, Public Use Data Files. Centers for Disease Control and Prevention, American Society for Reproductive Medicine, Society for Assisted Reproductive Technology, 2008 Assisted Reproductive Technology Success Rates: National Summary and Fertility Clinic Reports, Atlanta: US Department of Health and Human Services, 2010.
Pregnancy Outcomes by Maternal Age
The odds the pregnancy of a girl younger than 15 will result in a live birth are 1 in 2.3.
The odds the pregnancy of a teenage girl 15–17 will result in a live birth are 1 in 1.9.
The odds the pregnancy of a woman 18–19 will result in a live birth are 1 in 1.7.
The odds the pregnancy of a woman 20–24 will result in a live birth are 1 in 1.6.
The odds the pregnancy of a woman 25–29 will result in a live birth are 1 in 1.5.
The odds the pregnancy of a woman 30–34 will result in a live birth are 1 in 1.4.
The odds the pregnancy of a woman 35–39 will result in a live birth are 1 in 1.7.
The odds the pregnancy of a woman 40 or older will result in a live birth are 1 in 1.8.
The odds the pregnancy of a girl younger than 15 will result in an abortion are 1 in 2.3.
The odds the pregnancy of a teenage girl 15–17 will result in an abortion are 1 in 3.5.
The odds the pregnancy of a woman 18–19 will result in an abortion are 1 in 3.8.
The odds the pregnancy of a woman 20–24 will result in an abortion are 1 in 4.2.
The odds the pregnancy of a woman 25–29 will result in an abortion are 1 in 5.8.
The odds the pregnancy of a woman 30–34 will result in an abortion are 1 in 7.5.
The odds the pregnancy of a woman 35–39 will result in an abortion are 1 in 7.8.
The odds the pregnancy of a woman 40 or older will result in an abortion are 1 in 5.3.
The odds the pregnancy of a girl younger than 15 will result in fetal loss are 1 in 8.
The odds the pregnancy of a teenage girl 15–17 will result in fetal loss are 1 in 5.4.
The odds the pregnancy of a woman 18–19 will result in fetal loss are 1 in 7.1.
The odds the pregnancy of a woman 20–24 will result in fetal loss are 1 in 7.4.
The odds the pregnancy of a woman 25–29 will result in fetal loss are 1 in 7.1.
The odds the pregnancy of a woman 30–34 will result in fetal loss are 1 in 6.2.
The odds the pregnancy of a woman 35–39 will result in fetal loss are 1 in 3.7.
The odds the pregnancy of a woman 40 or older will result in fetal loss are 1 in 3.9.
Pregnancy Outcomes
The odds a pregnancy will result in a live birth: 1 in 1.6
The odds a pregnancy will result in an induced abortion: 1 in 5.3
The odds a pregnancy will result in fetal loss: 1 in 6
SOURCE: SJ Ventura, JC Abma, WD Mosher, “Estimated Pregnancy Rates for the United States, 1990–2005: An Update,” National Vital Statistics Reports 58(4), October 14, 2009.
SOURCE: SJ Ventura, JC Abma, WD Mosher, “Estimated Pregnancy Rates for the United States, 1990–2005: An Update,” National Vital Statistics Reports 58(4), October 14, 2009.
Odds of Having Had an Abortion by Age
The odds a teenage girl 15–19 has had 1 or more induced abortions are 1 in 72.2.
The odds a woman 20–24 has had 1 or more induced abortions are 1 in 11.9.
The odds a woman 25–29 has had 1 or more induced abortions are 1 in 8.9.
The odds a woman 30–34 has had 1 or more induced abortions are 1 in 6.7.
The odds a woman 35–39 has had 1 or more induced abortions are 1 in 5.4.
The odds a woman 40–44 has had 1 or more induced abortions are 1 in 6.
SOURCE: Book of Odds estimates based on Centers for Disease Control and Prevention, National Survey of Family Growth 2006–2008, Public Use Data Files.
The odds a woman who has given birth received amniocentesis during her most recent pregnancy: 1 in 72.5
SOURCE: JA Martin, BE Hamilton , PD Sutton, SJ Ventura, F Menacker, S Kirmeyer, ML Munson, “Births: Final Data for 2005,” National Vital Statistics Reports 56(6), December 5, 2007.
Abortions by Number
The odds a female 15–44 has never had an induced abortion are 1 in 1.1.
The odds a female 15–44 has had 1 induced abortion are 1 in 11.7.
The odds a female 15–44 has had 2 induced abortions are 1 in 44.3.
The odds a female 15–44 has had 3 or more induced abortions are 1 in 91.6.
SOURCE: Book of Odds estimates based on Centers for Disease Control and Prevention, National Survey of Family Growth 2006–2008, Public Use Data Files.
“Dr. Jackson 555–797–3905”
The odds a female who gives birth:
will first receive prenatal care within three months of conception: 1 in 1.4
will receive little or late (third trimester only) prenatal care: 1 in 14.1
SOURCE: JA Martin, BE Hamilton, PD Sutton, SJ Ventura, TJ Mathews, S Kirmeyer, MJK Osterman, “Births: Final Data for 2007,” National Vital Statistics Reports 58(24), August 2010.
Hop on the Scale: Pregnancy Weight Gain
The odds a pregnant female will gain:
less than 11 pounds: 1 in 12.5
11–20 pounds 1 in 6.1
21–30 pounds 1 in 3.4
31–40 pounds 1 in 3.9
41–98 pounds 1 in 4.8
SOURCE: JA Martin, BE Hamilton, TJ Mathews, SJ Ventura, MJK Osterman, S Kirmeyer, et al., “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011.
Will It Be a
Boy or a Girl?
A child’s gender is determined when a sperm fertilizes an egg. Normally the baby inherits one sex chromosome from each parent. The egg carries one of the mother’s two X (female) chromosomes; men have two sex chromosomes, one X and one Y (male), and each sperm cell carries one or the other. Without technical meddling, the odds are slightly higher that a newborn baby in the United States will be male (1 in 1.95) than female (1 in 2)—a disparity first demonstrated in London by John Arbuthnot in 1710 and found all around the world ever since.
Will the Third One
Be the Charm?
The odds a woman’s first two children will be boys are 1 in 3.8. The odds a woman’s first two children will be girls are 1 in 4.2. As the streaks lengthen, the difference in gender odds increases.
SOURCES: Book of Odds estimate based on JA Martin, BE Hamilton, PD Sutton, SJ Ventura, TJ Mathews, MJK Osterman, “Births: Final Data for 2008,” National Vital Statistics Reports 59(1), December 2010. Arbuthnot, “An Argument for Divine Providence, Taken from the Constant Regularity Observed in the Births of Both Sexes,” Philosophical Transactions of the Royal Society of London 27, 1710: 186–190.
Odds of Gender
The odds a woman’s…
first 2 children will be boys 1 in 3.8
first 3 children will be boys 1 in 7.5
first 4 children will be boys 1 in 14.6
first 5 children will be boys 1 in 28.5
first 6 children will be boys 1 in 55.7
first 2 children will be girls 1 in 4.2
first 3 children will be girls 1 in 8.6
first 4 children will be girls 1 in 17.6
first 5 children will be girls 1 in 36
first 6 children will be girls 1 in 73.8
SOURCE: Book of Odds estimate based on JA Martin, BE Hamilton, PD Sutton, SJ Ventura, F Menacker, S Kirmeyer, “Births: Final Data for 2004,” National Vital Statistics Reports 55(1), September 29, 2006.
Gestation Duration
The odds a baby will be born before 37 weeks of gestation are 1 in 8.2.
The odds a baby will be born before 28 weeks of gestation are 1 in 135.
The odds a baby will be born at 28–31 weeks of gestation are 1 in 81.6.
The odds a baby will be born at 32–33 weeks of gestation are 1 in 64.7.
The odds a baby will be born at 34–36 weeks of gestation are 1 in 11.5.
The odds a baby will be born at 37–41 weeks of gestation are 1 in 1.2.
The odds a baby will be born at 37–38 weeks of gestation are 1 in 3.6.
The odds a baby will be born at 39 weeks of gestation are 1 in 3.6.
The odds a baby will be born at 40–41 weeks of gestation are 1 in 3.7.
The odds a baby will be born at 42 or more weeks of gestation are 1 in 18.
SOURCE: JA Martin, BE Hamilton, SJ Ventura, MJK Osterman, S Kirmeyer, TJ Mathews, EC Wilson, “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011.
Birth Months
SOURCE: JA Martin, BE Hamilton, SJ Ventura, MJK Osterman, S Kirmeyer, TJ Mathews, EC Wilson, “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011.
The odds a person has the same birthday as at least 1 person in a group of 25 people: 1 in 15.1
SOURCE: Book of Odds estimate based on data from R Hocking, N Schwertman, “An Extension of the Birthday Problem to Exactly k Matches,” College Mathematics Journal 17(4), September 1, 1986.
Pregnancy Complications
The odds a woman who gives birth will develop a complication during her pregnancy:
Gestational diabetes: 1 in 21
Pregnancy-associated hypertension: 1 in 24.3
Placenta previa: 1 in 200
SOURCES: JA Martin, BE Hamilton, SJ Ventura, MJK Osterman, S Kirmeyer, TJ Mathews, EC Wilson, “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011. PubMed Health, “Placenta Previa,” http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001902/.
Time Warp
The odds a baby born in 1990 would be born in a clinic or doctor’s office: 1 in 3,686
The odds in 2009: 1 in 10,353
SOURCES: MF MacDorman, F Menacker, E Declercq, “Trends and Characteristics of Home and Other Out-of-Hospital Births in the United States, 1990–2006,” National Vital Statistics Reports 58(11), March 3, 2010, rev. August 30, 2010. JA Martin, BE Hamilton, SJ Ventura, MJK Osterman, S Kirmeyer, TJ Mathews, EC Wilson, “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011.
Coming Too Soon
In 1990, 1 in 9.4 births in the United States occurred prematurely, but by 2009, 1 in 8.2 births were premature. The March of Dimes estimates that rates of prematurity have risen 36% since 1987.
Even the norm of pregnancy duration has decreased. A typical pregnancy now lasts about 39 weeks, as opposed to the previous norm of 40, a gradual change that is estimated to have occurred between 1992 and 2002. The full length of pregnancy is important to give the baby time to develop and mature in the protected environment of the womb; any baby born before 37 weeks of gestation is considered premature or preterm, while babies born before 34 weeks into the pregnancy are considered early preterm.
SOURCES: JA Martin, BE Hamilton, PD Sutton, SJ Ventura, F Menacker, “Births: Final Data for 2005,” National Vital Statistics Reports 56(6), December 5, 2007. JA Martin, BE Hamilton, SJ Ventura, MJK Osterman, S Kirmeyer, TJ Mathews, EC Wilson, “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011. March of Dimes, “The Serious Problem of Premature Birth,” http://www.marchofdimes.com/mission/prematurity.html.
C–Section Birth Rates by State
The odds a birth in Alabama will be by Cesarean delivery are 1 in 2.8.
The odds a birth in Alaska will be by Cesarean delivery are 1 in 4.2.
The odds a birth in Arizona will be by Cesarean delivery are 1 in 3.6.
The odds a birth in Arkansas will be by Cesarean delivery are 1 in 2.9.
The odds a birth in California will be by Cesarean delivery are 1 in 3.
The odds a birth in Colorado will be by Cesarean delivery are 1 in 3.8.
The odds a birth in Connecticut will be by Cesarean delivery are 1 in 2.8.
The odds a birth in Delaware will be by Cesarean delivery are 1 in 2.8.
The odds a birth in the District of Columbia will be by Cesarean delivery are 1 in 3.1.
The odds a birth in Florida will be by Cesarean delivery are 1 in 2.6.
The odds a birth in Georgia will be by Cesarean delivery are 1 in 3.
The odds a birth in Hawaii will be by Cesarean delivery are 1 in 3.7.
The odds a birth in Idaho will be by Cesarean delivery are 1 in 4.1.
The odds a birth in Illinois will be by Cesarean delivery are 1 in 3.2.
The odds a birth in Indiana will be by Cesarean delivery are 1 in 3.3.
The odds a birth in Iowa will be by Cesarean delivery are 1 in 3.3.
The odds a birth in Kansas will be by Cesarean delivery are 1 in 3.3.
The odds a birth in Kentucky will be by Cesarean delivery are 1 in 2.8.
The odds a birth in Louisiana will be by Cesarean delivery are 1 in 2.5.
The odds a birth in Maine will be by Cesarean delivery are 1 in 3.4.
The odds a birth in Maryland will be by Cesarean delivery are 1 in 3.
The odds a birth in Massachusetts will be by Cesarean delivery are 1 in 3.
The odds a birth in Michigan will be by Cesarean delivery are 1 in 3.1.
The odds a birth in Minnesota will be by Cesarean delivery are 1 in 3.6.
The odds a birth in Mississippi will be by Cesarean delivery are 1 in 2.6.
The odds a birth in Missouri will be by Cesarean delivery are 1 in 3.2.
The odds a birth in Montana will be by Cesarean delivery are 1 in 3.4.
The odds a birth in Nebraska will be by Cesarean delivery are 1 in 3.2.
The odds a birth in Nevada will be by Cesarean delivery are 1 in 3.
The odds a birth in New Hampshire will be by Cesarean delivery are 1 in 3.2.
The odds a birth in New Jersey will be by Cesarean delivery are 1 in 2.5.
The odds a birth in New Mexico will be by Cesarean delivery are 1 in 4.4.
The odds a birth in New York will be by Cesarean delivery are 1 in 2.9.
The odds a birth in North Carolina will be by Cesarean delivery are 1 in 3.2.
The odds a birth in North Dakota will be by Cesarean delivery are 1 in 3.4.
The odds a birth
in Ohio will be by Cesarean delivery are 1 in 3.2.
The odds a birth in Oklahoma will be by Cesarean delivery are 1 in 2.9.
The odds a birth in Oregon will be by Cesarean delivery are 1 in 3.4.
The odds a birth in Pennsylvania will be by Cesarean delivery are 1 in 3.1.
The odds a birth in Rhode Island will be by Cesarean delivery are 1 in 3.
The odds a birth in South Carolina will be by Cesarean delivery are 1 in 2.8.
The odds a birth in South Dakota will be by Cesarean delivery are 1 in 4.4.
The odds a birth in Tennessee will be by Cesarean delivery are 1 in 3.
The odds a birth in Texas will be by Cesarean delivery are 1 in 2.8.
The odds a birth in Utah will be by Cesarean delivery are 1 in 4.4.
The odds a birth in Vermont will be by Cesarean delivery are 1 in 3.6.
The odds a birth in Virginia will be by Cesarean delivery are 1 in 2.9.
The odds a birth in Washington will be by Cesarean delivery are 1 in 3.4.
The odds a birth in West Virginia will be by Cesarean delivery are 1 in 2.8.
The odds a birth in Wisconsin will be by Cesarean delivery are 1 in 3.9.
The odds a birth in Wyoming will be by Cesarean delivery are 1 in 3.6.
SOURCE: JA Martin, BE Hamilton, SJ Ventura, MJK Osterman, S Kirmeyer, TJ Mathews, EC Wilson, “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011.
Changing Times
The United States has seen a dramatic rise in births by Cesarean section. The odds a birth would be by Cesarean delivery in 2009 were 1 in 3.1. In 1995, the odds a birth would be by Cesarean delivery were 1 in 4.8.
SOURCES: JA Martin, BE Hamilton, SJ Ventura, MJK Osterman, S Kirmeyer, TJ Mathews, EC Wilson, “Births: Final Data for 2009,” National Vital Statistics Reports 60(1), November 3, 2011. JA Martin, BE Hamilton, PD Sutton, SJ Ventura, F Menacher, S Kirmeyer, et al., “Births: Final Data for 2006.” National Vital Statistics Reports 57(7), January 7, 2009.
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