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Pregnancy Due Date Calculator References

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    • ACOG Committee Opinion: Method of Estimating Due Date Number 611 October 2014
    • ACOG Practice Bulletin. Clinical management guidelines for obstetricians-gynecologists. Number 55, September 2004 (replaces practice pattern number 6, October 1997). Management of Postterm Pregnancy.Obstet Gynecol. 2004;104:639-46.PMID:15339790 
    • Determination of gestational age by ultrasound. Butt K, Lim K; Society of Obstetricians and Gynaecologists of Canada. J Obstet Gynaecol Can. 2014 Feb;36(2):171-83.
    • Pregnancy dating by fetal crown-rump length: a systematic review of charts. Napolitano R, Dhami J, Ohuma EO, Ioannou C, Conde-Agudelo A, Kennedy SH, Villar J, Papageorghiou AT. BJOG. 2014 Apr;121(5):556-65. doi: 10.1111/1471-0528.12478. Epub 2014 Jan 6. Review.

    • Estimation of gestational age in early pregnancy from crown-rump length when gestational age range is truncated: the case study of the INTERGROWTH-21st Project. Ohuma EO, Papageorghiou AT, Villar J, Altman DG. BMC Med Res Methodol. 2013 Dec 7;13:151. doi: 10.1186/1471-2288-13-151.

    • Should a first trimester dating scan be routine for all pregnancies? Doubilet PM. Semin Perinatol. 2013 Oct;37(5):307-9. doi: 10.1053/j.semperi.2013.06.006.  

    • Human chorionic gonadotropin as a measure of pregnancy duration. Larsen J, Buchanan P, Johnson S, Godbert S, Zinaman M. Int J Gynaecol Obstet. 2013 Dec;123(3):189-95. doi: 10.1016/j.ijgo.2013.05.028. Epub 2013 Sep 3.

    • Accuracy of a home-based device for giving an early estimate of pregnancy duration compared with reference methods. Johnson SR, Godbert S, Perry P, Parsons P, Roberts L, Buchanan P, Larsen J, Alonzo TA, Zinaman M. Fertil Steril. 2013 Dec;100(6):1635-41.e1. doi: 10.1016/j.fertnstert.2013.08.031. Epub 2013 Sep 26.

    • Predicting date of birth and examining the best time to date a pregnancy. Khambalia AZ, Roberts CL, Nguyen M, Algert CS, Nicholl MC, Morris J. Int J Gynaecol Obstet. 2013 Nov;123(2):105-9. doi: 10.1016/j.ijgo.2013.05.007. Epub 2013 Aug 6.

    • Kramer MS, McLean FH, Boyd ME, Usher RH: The validity of gestational age estimation by menstrual dating in term, preterm and postterm gestations. JAMA 1988; 260:3306. PMID:3054193 

    • Savitz DA, Terry JW Jr, Dole N, Thorp JM Jr, Siega-Riz AM, Herring AH.Comparison of pregnancy dating by last menstrual period, ultrasound scanning, and their combination. Am J Obstet Gynecol. 2002 Dec;187(6):1660-6. PMID:12501080
    • Chervenak FA, Skupski DW, Romero R, et al: How accurate is fetal biometry in the assessment of fetal age?. Am J Obstet Gynecol 1998; 178:678.PMID:9579429 
    • Mongelli M, Wilcox M, Gardosi J.: Estimating the date of confinement: ultrasonographic biometery versus certain menstrual dates. Am J Obstet Gynecol 1996; 174:278.PMID:8572021 
    • Savitz DA, Terry Jr JW, Dole N, et al: Comparison of pregnancy dating by last menstrual period, ultrasound scanning, and their combination. Am J Obstet Gynecol 2002; 187:1660.PMID:12501080
    • Wilcox M, Gardosi J, Mongelli M, et al. Birth weight from pregnancies dated by ultrasonography in a multicultural British population. BMJ. Sep 4 1993;307(6904):588-91.PMID:8401014 
    • Ultrasonography in Pregnancy. ACOG Practice Bulletin No. 98. American College of Obstetricians and Gynecologists. Obstet Gynecol 2008;112: 1419–44. 
    • Rossavik IK, Fishburne JI. Conceptional age, menstrual age, and ultrasound age: a second-trimester comparison of pregnancies of known conception date with pregnancies dated from the last menstrual period. Obstet Gynecol. 1989 Feb;73(2):243-9.PMID: 2643067
    • Henderson SO, Mallon WK.Trauma in pregnancy. Emerg Med Clin North Am. 1998 Feb;16(1):209-28.PMID: 9496322
    • ACOG practice bulletin. Antepartum fetal surveillance. Number 9, October 1999 (replaces Technical Bulletin Number 188, January 1994). Clinical management guidelines for obstetrician-gynecologists. Int J Gynaecol Obstet. 2000 Feb;68(2):175-85. PMID: 10717828
    • Institute for Clinical systems Improvement. Routine Prenatal Care. 13th ed. August 2009. Available at:
    • Hay DL, Lopata A.Chorionic gonadotropin secretion by human embryos in vitro. J Clin Endocrinol Metab. 1988 Dec;67(6):1322-4.PMID: 2461389
    • Wilcox AJ, et al. Time of implantation of the conceptus and loss of pregnancy.N Engl J Med. 1999 Jun 10;340(23):1796-9.PMID: 10362823
    • Lohstroh P, et al. Daily immunoactive and bioactive human chorionic gonadotropin profiles in periimplantation urine samples. Biol Reprod. 2006 Jul;75(1):24-33. PMID: 16525035
    • Cervical insufficiency. ACOG Practice Bulletin No. 48. The American College of Obstetricians and Gynecologists. Obstet Gynecol 2003;102:1091–9. PMID: 15124633
    • Berghella V, et al., Does transvaginal sonographic measurement of cervical length before 14 weeks predict preterm delivery in high-risk pregnancies? Ultrasound Obstet Gynecol 2003;21:140-144. PMID: 12601834
    • Ultrasonography in Pregnancy. ACOG Practice Bulletin No. 101. American College of Obstetricians and Gynecologists. Obstet Gynecol 2009;113: 451–61. PMID: 19155920 
    • ACOG practice bulletin. Prevention of Rh D alloimmunization. Number 4, May 1999 (replaces educational bulletin Number 147, October 1990). Clinical management guidelines for obstetrician-gynecologists. American College of Obstetrics and Gynecology. Int J Gynaecol Obstet. 1999 Jul;66(1):63-70. PMID: 10458556
    • Fetal Lung Maturity. ACOG Practice Bulletin No. 97. American College of Obstetricians and Gynecologists. Obstet Gynecol 2008;112: 717–26PMID: 18757686
    • Altman DG, Chitty LS. New charts for ultrasound dating of pregnancy. Ultrasound Obstet Gynecol. 1997 Sep;10(3):174-91.
    • Mul T, Mongelli M, Gardosi J. A comparative analysis of second-trimester ultrasound dating formulae in pregnancies conceived with artificial reproductive techniques. Ultrasound Obstet Gynecol. 1996 Dec;8(6):397-402.
    • Westerway SC, Davison A, Cowell S. Ultrasonic fetal measurements: new Australian standards for the new millennium. Aust N Z J Obstet Gynaecol. 2000 Aug;40(3):297-302.