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Get answers to your female Fertility and Infertility questions.

Dr. McClamrock’s Bio | Q&A Archive

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Infertility in women - Introduction

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of female infertility.

Alternative Names

Pelvic inflammatory disease; Polycystic ovaries

Introduction:

Infertility is the failure of a couple to become pregnant after one year of regular, unprotected intercourse. In both men and women the fertility process is complex.

Infertility affects about 10% of all couples. Even under ideal circumstances, the probability that a woman will get pregnant during a single menstrual cycle is only about 30%. And, when conception does occur, only 50 - 60% of pregnancies advance beyond the 20th week. (The inability of a woman to produce a live birth because of abnormalities that cause miscarriages is called infecundity and is not discussed in detail in this report.)

About a third of infertility problems are due to female infertility, and another third are due to male infertility. In the remaining cases, infertility affects both partners or the cause is unclear. Although this report specifically addresses infertility in women, it is equally important for the male partner to be tested at the same time. [For more information, see In-Depth Report #67: Infertility in men.]

The Female Reproductive System

The primary organs and structures in the reproductive system are:

  • The uterus is a pear-shaped organ located between the bladder and lower intestine. It consists of two parts, the body and the cervix.
  • When a woman is not pregnant the body of the uterus is about the size of a fist, with its walls collapsed and flattened against each other. During pregnancy the walls of the uterus are pushed apart as the fetus grows.
  • The cervix is the lower portion of the uterus. It has a canal opening into the vagina with an opening called the os, which allows menstrual blood to flow out of the uterus into the vagina.
  • Leading off each side of the body of the uterus are two tubes known as the fallopian tubes. Near the end of each tube is an ovary.
  • Ovaries are egg-producing organs that hold 200,000 - 400,000 follicles (from folliculus, meaning "sack" in Latin). These cellular sacks contain the materials needed to produce ripened eggs, or ova.
  • The inner lining of the uterus is called the endometrium. During pregnancy, it thickens and becomes enriched with blood vessels to house and support the growing fetus. If pregnancy does not occur, the endometrium is shed as part of the menstrual flow. Menstrual flow also consists of blood and mucus from the cervix and vagina.
The uterus is a hollow muscular organ located in the female pelvis between the bladder and rectum. The ovaries produce the eggs that travel through the fallopian tubes. Once the egg has left the ovary it can be fertilized and implant itself in the lining of the uterus. The main function of the uterus is to nourish the developing fetus prior to birth.
Uterus

Reproductive Hormones. The hypothalamus (an area in the brain) and the pituitary gland regulate the reproductive hormones.


Brain-thyroid link
Click the icon to see an image of the hypothalamus and pituitary gland.

The pituitary gland is often referred to as the master gland because of its important role in many vital functions, many of which require hormones. In women, six key hormones serve as chemical messengers that regulate the reproductive system:

  • The hypothalamus first releases the gonadotropin-releasing hormone (GnRH).
  • This chemical, in turn, stimulates the pituitary gland to produce follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

Pituitary hormones
Click the icon to see an image of the pituitary gland.
  • Estrogen, progesterone, and the male hormone testosterone are secreted by the ovaries at the command of FSH and LH and complete the hormonal group necessary for reproductive health.

Ovulation. The process leading to fertility is very intricate. It depends on the healthy interaction of the reproductive organs and hormone systems in both the male and female. In addition, reproduction is limited by the phases of female fertility. Nevertheless, this process results in conception within a year for about 80% of couples. Only 15% conceive within a month of their first attempts, however, and about 60% succeed after 6 months.

A woman's ability to produce children occurs after she enters puberty and begins to menstruate. The process of conception is complex:

  • With the start of each menstrual cycle, follicle-stimulating hormone (FSH) stimulates several follicles to mature over a 2-week period until their eggs nearly triple in size. Only one follicle becomes dominant, however, during a cycle.
  • FSH signals this dominant follicle to produce estrogen, which enters the bloodstream and reaches the uterus. There, estrogen stimulates the cells in the uterine lining to reproduce, therefore thickening the walls.
  • Estrogen levels reach their peak around the 14th day of the cycle (counting days beginning with the first day of a period). At that time, they trigger a surge of luteinizing hormone (LH).

LH serves two important roles:

  • First, the LH surge around the 14th cycle day stimulates ovulation. It does this by causing the dominant follicle to burst and release its egg into one of the two fallopian tubes. Once in the fallopian tube, the egg is in place for fertilization.
  • Next, LH causes the ruptured follicle to develop into the corpus luteum. The corpus luteum provides a source of estrogen and progesterone during pregnancy.

Follicle development
Click the icon to see an image of the corpus luteum.

Fertilization. The so-called "fertile window" is 6 days long and starts 5 days before ovulation and ends the day of ovulation. Fertilization occurs as follows:

  • The sperm can survive for up to 3 days once it enters the fallopian tube. The egg survives 12 - 24 hours unless it is fertilized by a sperm.
  • If the egg is fertilized, about 2 - 4 days later it moves from the fallopian tube into the uterus where it is implanted in the uterine lining and begins its 9-month incubation.
  • The placenta forms at the site of the implantation. The placenta is a thick blanket of blood vessels that nourishes the fertilized egg as it develops.

Placenta
Click the icon to see an image of the placenta.
  • The corpus luteum (the yellow tissue formed from the ruptured follicle) continues to produce estrogen and progesterone during pregnancy.

If the egg is not fertilized, the corpus luteum degenerates into a form called the corpus albicans, and estrogen and progesterone levels drop. Finally, the endometrial lining sloughs off and is shed during menstruation.

Typical Menstrual Cycle

Menstrual Phases

Typical No. of Days

Hormonal Actions

Follicular (Proliferative) Phase

Cycle Days 1 - 6: Beginning of menstruation to end of blood flow.

Estrogen and progesterone start out at their lowest levels.

FSH levels rise to stimulate maturity of follicles. Ovaries start producing estrogen and levels rise, while progesterone remains low.

Cycle Days 7 - 13: The endometrium (the inner lining of the uterus) thickens to prepare for the egg implantation.

Ovulation

Cycle Day 14:

Surge in LH. Largest follicle bursts and releases egg into fallopian tube.

Luteal (Secretory) Phase, also known as the Premenstrual Phase

Cycle Days 15 - 28:

Ruptured follicle develops into corpus luteum, which produces progesterone. Progesterone and estrogen stimulate blanket of blood vessels to prepare for egg implantation.

If fertilization occurs:

Fertilized egg attaches to blanket of blood vessels that supplies nutrients for the developing placenta. Corpus luteum continues to produce estrogen and progesterone.

If fertilization does not occur:

Corpus luteum deteriorates. Estrogen and progesterone levels drop. The blood vessel lining sloughs off and menstruation begins.

Resources

References

Boomsma CM, Keay SD, Macklon NS. Peri-implantation glucocorticoid administration for assisted reproductive technology cycles. Cochrane Database Syst Rev. 2007 Jan 24;(1):CD005996.

El-Toukhy T, Sunkara SK, Khairy M, Dyer R, Khalaf Y, Coomarasamy A. A systematic review and meta-analysis of acupuncture in in vitro fertilisation. BJOG. 2008 Sep;115(10):1203-13. Epub 2008 Jul 23.

Jain T, Gupta RS. Trends in the use of intracytoplasmic sperm injection in the United States. N Engl J Med. 2007 Jul 19;357(3):251-7.

Jensen A, Sharif H, Svare EI, Frederiksen K, Kjaer SK. Risk of breast cancer after exposure to fertility drugs: results from a large Danish cohort study. Cancer Epidemiol Biomarkers Prev. 2007 Jul;16(7):1400-7. Epub 2007 Jun 21.

Lee SJ, Schover LR, Partridge AH, Patrizio P, Wallace WH, Hagerty K, et al. American Society of Clinical Oncology recommendations on fertility preservation in cancer patients. J Clin Oncol. 2006 Jun 20;24(18):2917-31.

Manheimer E, Zhang G, Udoff L, Haramati A, Langenberg P, Berman BM, Bouter LM. Effects of acupuncture on rates of pregnancy and live birth among women undergoing in vitro fertilisation: systematic review and meta-analysis. BMJ. 2008 Mar 8;336(7643):545-9. Epub 2008 Feb 7.

Norman RJ, Dewailly D, Legro RS, Hickey TE. Polycystic ovary syndrome. Lancet. 2007 Aug 25;370(9588):685-97.

Shevell T, Malone FD, Vidaver J, Porter TF, Luthy DA, Comstock CH, et al. Assisted reproductive technology and pregnancy outcome. Obstet Gynecol. 2005 Nov;106(5 Pt 1):1039-45.

Thessaloniki ESHRE/ASRM-Sponsored PCOS Consensus Workshop Group. Consensus on infertility treatment related to polycystic ovary syndrome. Fertil Steril. 2008 Mar;89(3):505-22. Epub 2008 Feb 20.

  • Reviewed last on: 10/21/2008
  • Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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