Early stages of pregnancy 5 weeks youtube,family planning trying to get pregnant,questions to ask your doctor when you are pregnant - 2016 Feature

As noted in previous Report Cards (2001, 2003, and 2004), stringent regulations on industrial and vehicle emissions have allowed the South Coast Air Basin (SoCAB) to make tremendous improvements in air quality over the past 30 years. This article focuses on health effects that ambient and traffic related air pollution has on pregnant women, their infants, and young children.
The time between conception and birth is perhaps one of the most vulnerable life stages, during which the environment may have tremendous immediate and lasting effects on health.
Early childhood is also a critical period for the continued development and maturation of several biological systems such as the brain, lung, and immune system and air toxics can impair lung function and neurodevelopment, or exacerbate existing conditions, such as asthma (Figure 2). Exactly what compounds in the ambient air most affect reproductive and children's health, and how these exposures result in restricted fetal growth, early parturition, and development of respiratory diseases remains largely unknown. A seminal paper published in 1977 by researchers in Los Angeles was the first to describe a possible association between air pollution at atmospheric levels and reduced birth weight. Mothers exposed to high levels of CO and particles during pregnancy are at higher risk of adverse birth outcomes, including preterm delivery, low birth weight, and congenital heart defects. In Los Angeles, we found that air pollution caused by traffic disproportionately affected women in low-income and disadvantaged neighborhoods. Michelle Wilhelm is an Assistant Professor In Residence in the Department of Epidemiology and member of the Center for Occupational and Environmental Health, School of Public Health, UCLA. A full-term pregnancy lasts approximately 270 days (approximately 38.5 weeks) from conception to birth. Virtually all of the effects of pregnancy can be attributed in some way to the influence of hormones—particularly estrogens, progesterone, and hCG. The placenta converts weak androgens secreted by the maternal and fetal adrenal glands to estrogens, which are necessary for pregnancy to progress. They induce the growth of fetal tissues and are necessary for the maturation of the fetal lungs and liver. They promote fetal viability by regulating progesterone production and triggering fetal synthesis of cortisol, which helps with the maturation of the lungs, liver, and endocrine organs such as the thyroid gland and adrenal gland. They stimulate maternal tissue growth, leading to uterine enlargement and mammary duct expansion and branching.
Relaxin, another hormone secreted by the corpus luteum and then by the placenta, helps prepare the mother’s body for childbirth.
The placenta takes over the synthesis and secretion of progesterone throughout pregnancy as the corpus luteum degenerates.
The anterior pituitary enlarges and ramps up its hormone production during pregnancy, raising the levels of thyrotropin, prolactin, and adrenocorticotropic hormone (ACTH).
The second and third trimesters of pregnancy are associated with dramatic changes in maternal anatomy and physiology.
During the first trimester, the mother does not need to consume additional calories to maintain a healthy pregnancy. Nausea and vomiting, sometimes triggered by an increased sensitivity to odors, are common during the first few weeks to months of pregnancy. A common gastrointestinal complaint during the later stages of pregnancy is gastric reflux, or heartburn, which results from the upward, constrictive pressure of the growing uterus on the stomach. The downward pressure of the uterus also compresses the urinary bladder, leading to frequent urination. Blood volume increases substantially during pregnancy, so that by childbirth, it exceeds its preconception volume by 30 percent, or approximately 1–2 liters. During the second half of pregnancy, the respiratory minute volume (volume of gas inhaled or exhaled by the lungs per minute) increases by 50 percent to compensate for the oxygen demands of the fetus and the increased maternal metabolic rate. The respiratory mucosa swell in response to increased blood flow during pregnancy, leading to nasal congestion and nose bleeds, particularly when the weather is cold and dry. The dermis stretches extensively to accommodate the growing uterus, breast tissue, and fat deposits on the thighs and hips. An increase in melanocyte-stimulating hormone, in conjunction with estrogens, darkens the areolae and creates a line of pigment from the umbilicus to the pubis called the linea nigra ([link]). Childbirth, or parturition, typically occurs within a week of a woman’s due date, unless the woman is pregnant with more than one fetus, which usually causes her to go into labor early.
First, recall that progesterone inhibits uterine contractions throughout the first several months of pregnancy. A common sign that labor will be short is the so-called “bloody show.” During pregnancy, a plug of mucus accumulates in the cervical canal, blocking the entrance to the uterus. Meanwhile, the posterior pituitary has been boosting its secretion of oxytocin, a hormone that stimulates the contractions of labor. Finally, stretching of the myometrium and cervix by a full-term fetus in the vertex (head-down) position is regarded as a stimulant to uterine contractions. The process of childbirth can be divided into three stages: cervical dilation, expulsion of the newborn, and afterbirth ([link]). For vaginal birth to occur, the cervix must dilate fully to 10 cm in diameter—wide enough to deliver the newborn’s head. True labor progresses in a positive feedback loop in which uterine contractions stretch the cervix, causing it to dilate and efface, or become thinner.
The amniotic membranes rupture before the onset of labor in about 12 percent of women; they typically rupture at the end of the dilation stage in response to excessive pressure from the fetal head entering the birth canal. The expulsion stage begins when the fetal head enters the birth canal and ends with birth of the newborn. In fewer than 5 percent of births, the infant is oriented in the breech presentation, or buttocks down. Vaginal birth is associated with significant stretching of the vaginal canal, the cervix, and the perineum.
Upon birth of the newborn’s head, an obstetrician will aspirate mucus from the mouth and nose before the newborn’s first breath.
The delivery of the placenta and associated membranes, commonly referred to as the afterbirth, marks the final stage of childbirth. It is important that the obstetrician examines the expelled placenta and fetal membranes to ensure that they are intact.


Although postpartum uterine contractions limit blood loss from the detachment of the placenta, the mother does experience a postpartum vaginal discharge called lochia. Hormones (especially estrogens, progesterone, and hCG) secreted by the corpus luteum and later by the placenta are responsible for most of the changes experienced during pregnancy. Toward the late stages of pregnancy, a drop in progesterone and stretching forces from the fetus lead to increasing uterine irritability and prompt labor.
Progesterone secreted by the placenta suppresses ________ to prevent maturation of ovarian follicles. How does the decrease in progesterone at the last weeks of pregnancy help to bring on labor?
Devin is 35 weeks pregnant with her first child when she arrives at the birthing unit reporting that she believes she is in labor. Janine is 41 weeks pregnant, and the mild contractions she has been experiencing “for days” have dilated her cervix to 2 cm.
The study of air pollution's impact on reproductive outcomes is still a developing area of science with many important questions unanswered, but more evidence is emerging that air pollution exposures in pregnancy and early childhood put children at higher risk of adverse health outcomes.
In fact, in one study, we linked residential traffic density to preterm and LBW which provides further evidence that traffic exhaust may be particularly important.
Air pollution exposure during early pregnancy may interfere with placental development and subsequent oxygen and nutrient delivery to the fetus throughout pregnancy, while the last trimester is important for fetal weight gain. Vehicle exhaust also contains very small or ultra fine particles (UFP), which have a high surface area.
CO is directly emitted by vehicle tailpipes and concentrations of this pollutant are elevated closer to heavy traffic roadways.
Ambient air pollution and adverse birth outcomes: Methodologic issues in an emerging field. Here you will learn about each month in pregnancy & how you may be feeling and how you and your baby develop.
Because it is easier to remember the first day of the last menstrual period (LMP) than to estimate the date of conception, obstetricians set the due date as 284 days (approximately 40.5 weeks) from the LMP. During weeks 7–12 from the LMP, the pregnancy hormones are primarily generated by the corpus luteum. It increases the elasticity of the symphysis pubis joint and pelvic ligaments, making room for the growing fetus and allowing expansion of the pelvic outlet for childbirth. Thyrotropin, in conjunction with placental hormones, increases the production of thyroid hormone, which raises the maternal metabolic rate. The most obvious anatomical sign of pregnancy is the dramatic enlargement of the abdominal region, coupled with maternal weight gain. These changes can sometimes prompt symptoms often referred to collectively as the common discomforts of pregnancy. This phenomenon is often referred to as “morning sickness,” although the nausea may persist all day. The same decreased peristalsis that may contribute to nausea in early pregnancy is also thought to be responsible for pregnancy-related constipation as pregnancy progresses. The greater blood volume helps to manage the demands of fetal nourishment and fetal waste removal. The growing uterus exerts upward pressure on the diaphragm, decreasing the volume of each inspiration and potentially causing shortness of breath, or dyspnea. Torn connective tissue beneath the dermis can cause striae (stretch marks) on the abdomen, which appear as red or purple marks during pregnancy that fade to a silvery white color in the months after childbirth. As a pregnancy progresses into its final weeks, several physiological changes occur in response to hormones that trigger labor. Approximately 1–2 days prior to the onset of true labor, this plug loosens and is expelled, along with a small amount of blood. At the same time, the myometrium increases its sensitivity to oxytocin by expressing more receptors for this hormone. The sum of these changes initiates the regular contractions known as true labor, which become more powerful and more frequent with time. Cervical stretching induces reflexive uterine contractions that dilate and efface the cervix further. It typically takes up to 2 hours, but it can last longer or be completed in minutes, depending in part on the orientation of the fetus. Until recent decades, it was routine procedure for an obstetrician to numb the perineum and perform an episiotomy, an incision in the posterior vaginal wall and perineum. Estrogen maintains the pregnancy, promotes fetal viability, and stimulates tissue growth in the mother and developing fetus.
She states that she has been experiencing diffuse, mild contractions for the past few hours. These are mild contractions that do not promote cervical dilation and are not associated with impending birth. These facts suggest that she is in labor, but that the labor is not progressing appropriately. However, studies of air pollution's effect on SIDS to date are equivocal[2], while results for particulate matter and respiratory infant mortality are fairly consistent and further supported by the strong and well established link between particles and adult mortality. But CO is not known to have any inflammatory effects in the lung, thus, we hypothesize that CO could be acting as a marker for other toxins in vehicles exhaust such as UFP and PAHs. Wilhelm's research focuses on the impact of environmental exposures, particularly air pollution, on perinatal and early childhood health. This assumes that conception occurred on day 14 of the woman’s cycle, which is usually a good approximation.
Progesterone secreted by the corpus luteum stimulates the production of decidual cells of the endometrium that nourish the blastocyst before placentation. This weight results from the growing fetus as well as the enlarged uterus, amniotic fluid, and placenta. During the second and third trimesters, the mother’s appetite increases, but it is only necessary for her to consume an additional 300 calories per day to support the growing fetus.


The source of pregnancy nausea is thought to be the increased circulation of pregnancy-related hormones, specifically circulating estrogen, progesterone, and hCG. In addition, the maternal urinary system processes both maternal and fetal wastes, further increasing the total volume of urine. In conjunction with increased blood volume, the pulse and blood pressure also rise moderately during pregnancy.
During the last several weeks of pregnancy, the pelvis becomes more elastic, and the fetus descends lower in a process called lightening.
As labor nears, oxytocin begins to stimulate stronger, more painful uterine contractions, which—in a positive feedback loop—stimulate the secretion of prostaglandins from fetal membranes. However, it varies widely and may take minutes, hours, or days, depending in part on whether the mother has given birth before; in each subsequent labor, this stage tends to be shorter. In addition, cervical dilation boosts oxytocin secretion from the pituitary, which in turn triggers more powerful uterine contractions. Fetal distress, measured as a sustained decrease or increase in the fetal heart rate, can result from severe contractions that are too powerful or lengthy for oxygenated blood to be restored to the fetus. The vertex presentation known as the occiput anterior vertex is the most common presentation and is associated with the greatest ease of vaginal birth. Uterine contractions continue for several hours after birth to return the uterus to its pre-pregnancy size in a process called involution, which also allows the mother’s abdominal organs to return to their pre-pregnancy locations.
Thick, dark, lochia rubra (red lochia) typically continues for 2–3 days, and is replaced by lochia serosa, a thinner, pinkish form that continues until about the tenth postpartum day.
Progesterone prevents new ovarian follicles from developing and suppresses uterine contractility. Maternal blood volume increases by 30 percent during pregnancy and respiratory minute volume increases by 50 percent. Examination reveals, however, that the plug of mucus blocking her cervix is intact and her cervix has not yet begun to dilate. Pitocin is a pharmaceutical preparation of synthetic prostaglandins and oxytocin, which will increase the frequency and strength of her contractions and help her labor to progress to birth.
These studies nevertheless have not been able to identify the specific components of particulate matter, nor elucidate the mechanism by which these pollutants affect health in children and infants, which may be different from adults. PAHs may also interfere with placental development and fetal growth early in pregnancy, but more studies are needed to understand the mechanisms that can cause this to happen. She published the first study examining associations between residential proximity to traffic during pregnancy and adverse birth outcomes and is particularly interested in how Geographic Information Systems and other novel approaches such as biomarkers can be used to estimate exposure to traffic generated air pollution in large epidemiologic studies. The 40 weeks of an average pregnancy are usually discussed in terms of three trimesters, each approximately 13 weeks. As the placenta develops and the corpus luteum degenerates during weeks 12–17, the placenta gradually takes over as the endocrine organ of pregnancy.
This hormone decreases in late gestation, allowing uterine contractions to intensify and eventually progress to true labor. Additional breast tissue and dramatically increased blood volume also contribute to weight gain ([link]).
As the fetus grows, the uterus compresses underlying pelvic blood vessels, hampering venous return from the legs and pelvic region.
The increasing ratio of estrogen to progesterone makes the myometrium (the uterine smooth muscle) more sensitive to stimuli that promote contractions (because progesterone no longer inhibits them). Such a situation can be cause for an emergency birth with vacuum, forceps, or surgically by Caesarian section. The fetus faces the maternal spinal cord and the smallest part of the head (the posterior aspect called the occiput) exits the birth canal first. Both an episiotomy and a perineal tear need to be sutured shortly after birth to ensure optimal healing.
After this period, a scant, creamy, or watery discharge called lochia alba (white lochia) may continue for another 1–2 weeks. In addition to her work on birth outcomes, she is also currently involved in several studies concerning air pollution and exacerbation of asthma in Californian children. During the second and third trimesters, the pre-pregnancy uterus—about the size of a fist—grows dramatically to contain the fetus, causing a number of anatomical changes in the mother ([link]).
Surprisingly, fat storage accounts for only approximately 2.3 kg (5 lbs) in a normal pregnancy and serves as a reserve for the increased metabolic demand of breastfeeding. Moreover, in the eighth month of pregnancy, fetal cortisol rises, which boosts estrogen secretion by the placenta and further overpowers the uterine-calming effects of progesterone. Although suturing the jagged edges of a perineal tear may be more difficult than suturing an episiotomy, tears heal more quickly, are less painful, and are associated with less damage to the muscles around the vagina and rectum. In addition to promoting survival of the corpus luteum, hCG stimulates the male fetal gonads to secrete testosterone, which is essential for the development of the male reproductive system.
In addition to the pituitary hormones, increased parathyroid levels mobilize calcium from maternal bones for fetal use. Some women may feel the result of the decreasing levels of progesterone in late pregnancy as weak and irregular peristaltic Braxton Hicks contractions, also called false labor. Given the importance of oxytocin and prostaglandins to the initiation and maintenance of labor, it is not surprising that, when a pregnancy is not progressing to labor and needs to be induced, a pharmaceutical version of these compounds (called pitocin) is administered by intravenous drip.
Delivery of the placenta marks the beginning of the postpartum period—the period of approximately 6 weeks immediately following childbirth during which the mother’s body gradually returns to a non-pregnant state.
If the placenta does not birth spontaneously within approximately 30 minutes, it is considered retained, and the obstetrician may attempt manual removal.
She currently teaches courses in Environmental, Occupational and Reproductive Epidemiology in the School of Public Health, in addition to working on her research.



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