Text B Routine Prenatal Care

First Trimester

Despite the dramatic and vulnerable changes that the conceptus undergoes in the first 14 weeks of gestation，many patients are unaware of their pregnancy or delay seeking prenatal care．Emerging evidence suggests that it is during this period the foundations of a successful pregnancy and even the future health of the adult individual are set．Although most pregnant women would deliver healthy infants without any prenatal care，obstetric care is designed to promote optimal health throughout the course of normal pregnancy while screening for and managing any complications that may develop．Roughly one fourth of pregnant women do not receive care during the first trimester．

Relevant pathophysiology．During the first trimester of gestation，the developing embryo implants in the endometrium（except in the case of ectopic pregnancies），the placental attachment to the mother is created，and the major structures and organs of the body are formed．1 The developing embryo is sensitive to exposures to toxins，medications，and radiation and the effects of maternal conditions that can disrupt this process．Errors in this process may result in major disruptions in structure or function of the fetus or even the complete loss of the pregnancy．About the 12thweek of gestation，the placenta takes over hormonal support for the pregnancy from the corpus luteum．If this transition does not happen smoothly，the pregnancy can be lost．

Strategies．At the first prenatal visit，a comprehensive history should be taken，including previous pregnancy outcome（s），if any，and any medical or surgical conditions that may affect pregnancy．This should include past medical history，information pertinent to genetic screening，and any events in the course of the current pregnancy．Special attention should also be given to diet， tobacco or alcohol use，and any medications or substances used．Routine laboratory studies should be ordered，and the patient should be given instructions concerning routine prenatal care，warning signs of complications，and who to contact with questions or problems．A complete physical examination should be performed，including a Pap test and tests for sexually transmitted diseases．

It is important early in the course of pregnancy to establish an accurate gestational age and estimated date of confinement（EDC，or due date）．This information is needed to manage later complications of pregnancy and to determine the timing of evaluations（e．g．neural tube screening，1－hour glucose challenge testing，Rh prophylaxis）．2 If needed，transvaginal and transabdominal ultrasonographic techniques allow gestational age determination with approximately 7 to 10 day accuracy when performed during the first trimester．

At each visit，the patient should be asked about any problems such as vaginal bleeding，nausea／vomiting，dysuria，or vaginal discharge．Each prenatal visit should include measurements of blood pressure and weight and an assessment for edema（blood pressure generally declines at the end of the first trimester，increasing again in the third trimester）．A clean－catch urine sample should be tested（most often by dipstick）for protein and signs of infection． Obstetric assessments should include uterine size by pelvic examination or fundal height measurement and documentation of the presence and rate of fetal heart tones by the use of a fetal Doppler ultrasound device．3 Patients at low risk may be followed at 4－week intervals until 28 weeks of gestation．

Second Trimester

During the second trimester（about 14 to 28 weeks of gestation）the fetus continues to grow and develop，organ function becomes more normal，and the growing uterus is more apparent．Prenatal care during this period is directed toward monitoring the progress of the pregnancy and detecting treatable complications．4

Relevant pathophysiology．During the second trimester of gestation，levels of human chorionic gonadotropin plateau and often decline，easing many of the early maladies of pregnancy such as breast tenderness and morning sickness， although the growing uterus may now bring on heartburn and constipation．The risk of early pregnancy loss has passed（except for infrequent cases of cervical incompetence and preterm labor）and the fetus grows from being just 3 inches in length at 14 weeks to weighing roughly 2 pounds by the end of the second trimester．There is an increase in maternal blood volume and cardiac output （20％or greater）to feed the needs of the growing pregnancy．The first detectable movements of the baby（quickening）occur during this trimester （generally about 16 to 20 weeks of gestation）and the female fetus has the most egg cells of any point in her life（oocytes peak at 6 million to 7 million at about 16 to 20 weeks of gestation，declining to about 1 million at birth）．Fetal viability（ability to survive apart from the mother）begins at about 24 weeks， although intact survival at this stage is unlikely．Toward the end of this trimester maternal hemorrhoids and low back pain may occur．Colostrum（the first form of breast milk）is present by 26 weeks of gestation．

Strategies．Screening for open neural tube and other defects［via measurement of maternal serumαfetoprotein（AFP）and other markers］is generally performed between 15 and 20 weeks．

Toward the end of this trimester，a repeat measurement of hemoglobin is taken，glucose screening（usually 1－hour glucose challenge at 28 weeks for patients at low risk）is performed，and prophylactic treatment with Rh D immune globulin is given for patients who are Rh negative．

Patients at low risk may be followed at 4－week intervals until the end of this trimester．Routine use of ultrasonography to screen low－risk pregnancies is not currently recommended．

Third Trimester

During the third trimester（about 29 to 40 weeks of gestation）the fetus continues to grow and develop with full maturation in organ function being established，maternal physiology continuing to change，and the cervix and uterus preparing for the processes of childbirth．Prenatal care during this period continues to be directed toward monitoring the progress of the pregnancy and detecting treatable complications．It is during the third trimester that the uterus and fetus prepare for labor and delivery．It is also during this phase of pregnancy that complications such as pre－eclampsia，bleeding，complications of diabetes or hypertension，abnormalities of growth or amniotic fluid，and preterm labor may arise．

Relevant pathophysiology．During the third trimester of gestation，the dramatic growth of the fetus continues as it gains its final birthweight and its organs prepare for full function as an autonomous individual．Maternal blood volume almost doubles，and cardiac output reaches its maximum．By the 29th week，the fetus has 300 bones，although many of them will fuse after birth， leaving the adult total of 206．The fetal presenting part begins to descend into the maternal pelvis in the last month of pregnancy，resulting in a decline in fundal height，improved respiratory and gastric function，and greater pelvic pressure and discomfort．Late in this trimester，changes in the cervix begin the preparations for dilation and effacement during labor and delivery．5

Strategies．For selected patients，“kick counts”may be used to assess the overall health of the fetus．In general，the detection of more than four fetal movements over the course of an hour indicates a healthy fetus．All patients should be encouraged to monitor their baby's activity levels and be evaluated for any prolonged reduction or absence in activity．

Planning and preparation for breastfeeding should be undertaken during this trimester．No special physical preparation is needed for successful breastfeeding，but discussion，questions，and the acquisition of needed supplies （e．g．nursing bra）are best taken care of before delivery．

For high－risk pregnancies，antenatal testing（nonstress test，contraction stress test，and biophysical profile）should be considered and implemented as indicated．

Patients at low risk may be followed at 2－week intervals until approximately the 36thweek，when visits occur at weekly intervals（or more often as dictated by the course of the pregnancy）．

（1，270 words）

New Words and Phrases

prenatal［priː'neɪtəl］a． 产前的；出生以前的

trimester［traɪ'mestə］n． 三个月

conceptus［kən'septəs］n． 孕体

obstetric［əb'stetrɪk］a． 产科的；产科学的

optimal［'ɒptəməl］a． 最理想的

embryo［'embrɪəʊ］n． 胚胎

endometrium［,endəʊ'miːtrɪəm］n． 子宫内膜

ectopic［ek'tɒpɪk］a． 异位的，异常的

placental［plə'sentəl］a． 胎盘的

placenta［plə'sentə］n． 胎盘

corpus luteum［'kɔːpəs'luːtɪəm］ 黄体

pertinent［'pзːtɪnənt］a． 有关的

gestational［dʒe'steɪʃənəl］a． 妊娠（期）的；怀孕（期）的

confinement［kən'faɪnmənt］n． 分娩；限制

transvaginal［træns'vædʒɪnəl］a． 经阴道的

transabdominal［'træns,æb'dɒmɪnəl］a． 经腹的

dysuria［dɪs'jʊərɪə］n． 排尿困难

discharge［dɪs'tʃɑːdʒ］n． 排出，流出；分泌物

edema［iː'diːmə］n． 水肿

fundal height［fʌndəl haɪt］ 宫高

Doppler［'dɒplə］a． 多普勒的

plateau［'plætəʊ］v． 达到稳定水平（或阶段）

malady［'mælədɪ］n． 病

oocyte［'əʊəsaɪt］n． 卵母细胞

intact［ɪn'tækt］a． 未受损的；完整的

hemorrhoid［'hemərɒɪd］n． 痔疮

colostrum［kə'lɒstrəm］n． 初乳

fetoprotein［,fiːtə'prəʊtiːn］n． 胎蛋白

negative［'neɡətɪv］a． 阴性的

pre－eclampsia［,priːɪ'klæmpsɪə］n． 先兆子痫

amniotic［,æmnɪ'əʊtɪk］a． 羊膜的

amniotic fluid 羊水

autonomous［ɔː'tɒnəməs］a． 自主性的

respiratory［'respɪrətərɪ］a． 呼吸的

gastric［'ɡæstrɪk］a． 胃的

effacement［ɪ'feɪsmənt］n． 消失

antenatal［æntɪ'neɪtəl］a． 产前的；出生前的

biophysical［baɪəʊ'fɪzɪkəl］a． 生物物理学的

biophysical profile［baɪəʊ'fɪzɪkəl'prəʊfaɪl］n． 生物物理评估

implement［'ɪmplɪmənt］v． 履行；贯彻；完成

Notes

1．During the first trimester of gestation，the developing embryo implants in the endometrium（except in the case of ectopic pregnancies），the placental attachment to the mother is created，and the major structures and organs of the body are formed．

参考译文：在孕早期，发育中的胚胎在子宫内膜着床（除外异位妊娠的情况），附着于母体的胎盘开始出现，身体的主要结构和器官逐渐形成。

此句是并列句，developing embryo，placental attachment和major structures and organs分别是3个子句的主语；implants，is created和are formed分别是3个子句的谓语。

2．It is important early in the course of pregnancy to establish an accurate gestational age and estimated date of confinement（or due date）．This information is needed to manage later complications of pregnancy and to determine the timing of evaluations（e．g．neural tube screening，1－hour glucose challenge testing，Rh prophylaxis）．

参考译文：在妊娠早期，确定孕周和估算分娩日期（或预产期）很重要。这些数据资料对处理妊娠后期并发的复杂情况及确定具体的孕期评估检查时间（如神经管筛查，1小时葡萄糖激发试验，Rh血型不合溶血病预防检查）都是必要的。

在第1句中，to establish an accurate gestational age and estimated date of confinement（or due date）是不定式短语做主语，It是形式主语。gestational age意为“孕周”；confinement意为“分娩”。e．g．Her confinement was approaching．

3．Obstetric assessments should include uterine size by pelvic examination or fundal height measurement and documentation of the presence and rate of fetal heart tones by the use of a fetal Doppler ultrasound device．

参考译文：产科评估应包括通过骨盆检查或宫高测量以确定子宫大小和使用多普勒超声设备以监测和记录胎心音和胎心率。

by pelvic examination or fundal height measurement和by the use of a fetal Doppler ultrasound device是两个介词短语做定语，表方式，意为“通过或使用……方法或途径”。

4．During the second trimester of gestation，levels of human chorionic gonadotropin plateau and often decline，easing many of the early maladies of pregnancy such as breast tenderness and morning sickness，although the growing uterus may now bring on heartburn and constipation．

参考译文：在孕中期，虽然子宫增长可能会引起胃灼热和便秘，但是人体绒毛膜促性腺激素水平稳定并往往开始下降，因此缓解了许多孕早期的症状，如乳房触痛和晨间呕吐。

主句中levels of human chorionic gonadotropin是主语；plateau和decline做并列谓语，意指“稳定”和“下降”；easing．．．and morning sickness是分词短语作结果状语；although引导让步状语从句。

5．Late in this trimester，changes in the cervix begin the preparations for dilation and effacement during labor and delivery．

参考译文：在这一阶段（孕晚期）后期，宫颈出现变化并开始为分娩和生产做子宫颈扩张和子宫颈消失的准备。

句中dilation and effacement意为“（子宫颈的）扩张和消失”；labor and delivery意为“分娩和生产”。

Exercises

Ⅰ．Answer the following questions．

1．Why is obstetric care still important although most pregnant women would deliver healthy infants without any prenatal care？

2．At each trimester of routine prenatal care，what problems should be asked for the patients？

3．What prominent changes will be shown concerning both the embryo（or fetus）and maternal physiology from the first trimester to the third one？

4．How shall we treat patients at low－risk pregnancies and at high－risk ones especially at different phases？

5．How often should the prenatal care be taken and what kind of special attention，measurement and physical examination should also be given？

Ⅱ．Decide whether the following statements are True or False．

1．About the 12thweek of gestation，the placenta takes over hormonal support for the pregnancy from the corpus luteum．

2．It is important early in the course of pregnancy to apply transvaginal and transabdominal ultrasonographic techniques to gestational age determination with approximately 7to10 day accuracy．

3．Each prenatal visit should include measurements of blood pressure and weight，an assessment for edema and a test of a clean－catch urine sample for protein and signs of infection．

4．Fetal viability begins at about 24 weeks，so intact survival at this stage is very likely．

5．The fetal presenting part begins to descend into the maternal pelvis in the last month of pregnancy，resulting in a decline in fundal height，improved respiratory and gastric function and greater pelvic pressure．