Answer: <p><strong>Physiological changes in the reproductive system</strong></p>
<ul>
<li><strong>Vulva:</strong></li>
</ul>
<p>Vulva becomes edematous and hyperemic, superficial varicosities may appear especially in multiparae. Libiaminora is pigmented and hypertrophied.</p>
<ul>
<li><strong>Vagina:</strong></li>
</ul>
<p>There is marked increased blood supply to the vagina in pregnancy which causes the following changes.</p>
<ol>
<li>Softening of the vaginal tissues which allow for easier distension in labor.</li>
<li>Purple discoloration of the vagina which is called jacquemier&rsquo;s sign.</li>
<li>Pulsation of the uterine arteries feels through the lateral fornices called osiander&rsquo;s sign.</li>
<li>Increase vaginal discharge normally white in color the pH becomes acidic (3.5 &ndash; 6).</li>
</ol>
<ul>
<li><strong>Changes in cervix:</strong></li>
</ul>
<p>During pregnancy, cervix becomes vascular, edematous and soft, length becomes double and volume increase throughout the pregnancy. The cervix Contains more fibrous tissue and less muscular tissue than the body of uterus. There is slightly increase in width of a cervix. On examination, it will be purple and soft.</p>
<p>Under the influence of progesterone, endocervical cells secret mucous which becomes thicker and viscous during pregnancy. The thickened mucous from the cervical plug called the operculum,which protects from ascending infection.</p>
<p>In late pregnancy, softening of the cervix occurs in response to increasing painless contraction, prostaglandin release from the local tissue and reduced collagen concentration within the cervix and more distensible in readiness for the onset of labor.</p>
<ul>
<li><strong>The body of uterus</strong>:</li>
</ul>
<p>After the conception , the uterus develops to provide a nutritive and protective environment in which the fetus will develop and growth.</p>
<ol>
<li>Decidua: The decidua is a name given to the endometrium during pregnancy; progesterone and estrogen initially produce by corpus luteum cause the decidua to become thicker, richer and more vascular at the fundus and in the upper body of the uterus. These are the usual site of implantation. The decidua is less thin and less vascular in the lower pole of the uterus. The decidua provides a glycogen-rich environment for the blastocyst until the trophoblast cells begin to form the placenta. When the placenta is formed; it is able to produce its own hormone.</li>
<li>Myometrium: estrogen is responsible for the growth of uterine muscle. Increase in size of the muscle fibers is known as hypertrophy and increase in their number is referred to as hyperplasia. The uterus continues to grow in this way for the first 20 weeks. After this, it stretches to accommodate its contents increase in weight from 60 to900 gm, increase in size from 7.5cm * 5cm *2.5cm to 30cm *22cm *20cm. The uterus is able to stretch in this way because progesterone encourages relaxation of smooth muscles. But even at 16 weeks of gestation, uterus begins to generate small waves of contraction as Braxton hick&rsquo;s contraction. Contraction is usually painless although some women do experience pain. Braxton hick&rsquo;s contraction last approximately 60 seconds continues throughout pregnancy and later it changes into a contraction of labour.</li>
<li>Muscle layer: the inner circular layer surrounds the cornu, the lower uterine segment, and cervix. This circular Layer involved in stretching of the lower segment and the cervix during labor.</li>
</ol>
<p>The middle oblique layer is involved in the contraction necessary to expel the fetus at the end of pregnancy. This action is also necessary to entrap and enmesh bleeding vessels and ligate them after the placenta is delivered.</p>
<p>The outer longitudinal layer, muscle fiber contact and retract during labor causing the upper segment too thicken. The thick upper segment acts as a piston to force the fetus into the respective passive lower segment to expel the baby.</p>
<ol start="4">
<li>Perimetrium: It is a layer of peritoneum . It does not totally cover the uterus. It allows for the unrestricted Growth of the uterus.</li>
</ol>
<ul>
<li><strong>Uterine growth</strong>:</li>
</ul>
<p>During the first 12 weeks of pregnancy, the uterus enlarges into the pelvic cavity. At 12 weeks, it rises into the abdominal cavity and the fundus can be palpated just above the symphysis pubis. The uterus losses its normal position and become erect, though it may move slightly to the right but after 20^th weeks of pregnancy, It returns to its normal position.</p>
<p>By 16^th weeks, the uterus is an almost half way between the symphysis pubis and umbilicus. At 20^th weeks, it is about 1&rdquo; (finger) below the umbilicus. At 24^thweeks, it is 1 finger above the umbilicus. Sometimes between 16-20 weeks, when the growing uterus comes into the contact with the mother abdominal walls, the fetal movement may be felt by the mother, sensation of the movement is known as &ldquo;quickening&rdquo;, which means life. At 30 weeks , the fundus is midway between the umbilical and xiphisternum. At 36 weeks, the fundus raises the level of the xiphisternum and may become engaged in the pelvis in which the level of pelvic falls about that of 34 weeks of pregnancy.</p>
<ul>
<li><strong>Changes in uterine shape:</strong></li>
</ul>
<p>Healthy growth of the fetus required adequate. After conception, the embedded blastocyst demands little space but the upper part of the uterus begin to enlarge due to an effect of estrogen. The uterus changes into a globular shape in early pregnancy from the pear shaped during 12^th weeks of pregnancy to anticipate the fetal growth and also accommodated increasing amount of liquor and placental tissue. This causes pressure on the other pelvic organ.</p>
<p>The lower part of the uterus consisting of the isthmus softens and elongates from its original size until 10 weeks of pregnancy when it measure 25mm giving an appearance of a stalk below the globular upper segment.</p>