PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Fertilization rate”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2002

Poor semen quality may contribute to recent decline in fertility rates.

During past decades, we have witnessed a remarkable decline in fertility rates (number of births per 1000 women of reproductive age) in the industrialized world. It seems beyond doubt that the enormous social changes of our societies play the major role in this decline, but can it be attributed to changing social structures alone or is a reduced fecundity in the population also a factor? To address this we have focused on trends in teenage pregnancies (which to a large extent are unplanned). During the period in question fertility rates among 15-19 year old Danish women have been falling and the decline in fertility rate is not counterbalanced by an increase in the rate of induced abortion. When seen together with recent results from Denmark, which have shown that more than 30% of 19 year old men from the general population now have sperm counts in the subfertile range, we argue that this fall may not be attributable to social factors, changes in conception practices or diminished sexual activity alone. It seems reasonable also to consider widespread poor semen quality among men as a potential contributing factor to low fertility rates among teenagers. Due to the concern caused by the low sperm count among younger Danish men, the Danish Ministries of Health and Environment have launched a surveillance programme which includes an annual examination of the semen quality in 600 young Danes from the general population. We propose that researchers in other countries with low and falling fertility rates among young women should consider the possibility that semen quality of their younger male cohorts may also have deteriorated.

Adolescent↗
PubMed1989

Improved sperm concentration, motility, and fertilization rates following Ficoll treatment of sperm in a human in vitro fertilization program.

Duplicate sperm samples from the spouses of 54 patients admitted to an in vitro fertilization program were prepared by the swim-up and a simplified procedure using Ficoll. Cellsoft (CRYO Resources, New York, NY) sperm curvilinear velocities (microns/sec) and mean amplitude of lateral head displacement values (microns) equivalent to grade 1 and 2 visual sperm motility were significantly higher for Ficoll as compared with swim-up samples (P less than 0.01). Fertilization rates were significantly higher in the Ficoll as compared with the swim-up group for poor semen samples (grade less than 2: 58% versus 24%; P less than 0.01) and normal semen samples (grade greater than or equal to 2: 85% versus 78%; P less than 0.05). Ficoll sperm separation appears to be an excellent method of yielding increased fertilization rates in in vitro fertilization programs.

Female↗
PubMed1995

Manipulation of sperm before intracytoplasmic sperm injection improves fertilization rates.

OBJECTIVE: To determine the effect of sperm manipulation before intracytoplasmic sperm injection (ICSI) on fertilization rates. DESIGN: Three methods of sperm manipulation before direct ICSI were compared in two sibling oocyte trials. SETTING: In vitro fertilization unit within a teaching hospital. PATIENTS: Patients undergoing infertility treatment using ICSI. INTERVENTIONS: Oocytes were inseminated by ICSI. MAIN OUTCOME MEASURE: Fertilization rate. RESULTS: In the first trial, a standard manipulation technique gave a 67% fertilization rate compared with 64% with a minimal manipulation technique. In the second trial the standard technique gave a significantly greater fertilization rate compared with no prior manipulation (67% versus 45%). CONCLUSIONS: Manipulation of sperm before direct ICSI is not mandatory for fertilization but significantly improves the fertilization rate.

Cytoplasm↗
PubMed1991

Fertility rates in 238 HIV-1-seropositive women in Zaire followed for 3 years post-partum.

Birth-control use and fertility rates were prospectively determined in 238 HIV-1-seropositive and 315 HIV-1-seronegative women in Kinshasa, Zaire, during the 36-month period following the delivery of their last live-born child. No women delivered children during the first follow-up year. Birth-control utilization rates (percentage use during total observation time) and fertility rates (annual number of live births per 1000 women of child-bearing age) in the second year of follow-up were 19% (107.4 per 1000) for HIV-1-seropositive women and 16% (144.7 per 1000) for HIV-1-seronegative women. In the third year of follow-up these rates were 26 (271.0 per 1000) and 16% (38.6 per 1000) for HIV-1-seropositive and HIV-1-seronegative women, respectively (P less than 0.05 for the difference in birth-control utilization and fertility rates between seropositive and seronegative women in the third year of follow-up). Seven (2.9%) of the 238 HIV-1-seropositive women initially included in the study brought their sex partners in for HIV-1 testing; three (43%) of these men were found to be HIV-1-seropositive. New HIV-1 infection did not have a dramatic effect on the fertility of seropositive women. The nearly uniform unwillingness of HIV-1-seropositive women to inform husbands or sexual partners of their HIV-1 serostatus accounted in large part for the disappointingly high fertility rates in seropositive women who had been provided with a comprehensive program of HIV counseling and birth control. Counseling services for seropositive women of child-bearing age which do not also include these women's sexual partners are unlikely to have an important impact on their high fertility rates.

AIDS-Related Complex↗
PubMed2003

[Fertilization rate analysis as a predictive variable for an in-vitro fertilization program success].

OBJECTIVE: Determining if fertilization rates can be used as a predictive factor for pregnancy induction in ETIVF-ICSI programs. TYPE OF STUDY: Retrospective, observational and descriptive. MATERIALS AND METHODS: Six hundred and seventy nine cycles of the in vitro fertilization program, using long protocol hypophyseal suppression, stop, or antagonsits, were included. Ovarian stimulation was carried out with menotropines or recombinant FSH. Those patients whose cycle was stopped due to the lack of follicular development were excluded. Variables under study were: age, fertilization percentage, pregnancy rate, pre-ovulatory estradiol levels, number and quality of captured oocytes, transferred embrios and endometrial thickness on the day of transference and the presence of pregnancy. The Pearson P Test with a 95% confidence interval and the Student T Test used to establish differences with a 95% confidence interval statistical analyses were applied. RESULTS: Six hundred and seventy nine cycles were studied, 487 of which used the conventional fertilization method, and 192 used the ICSI method. Mean age among patients was 34 +/- 1.1 years old, with pre-ovulatory estradiol levels of 4,023 +/- 1,134 pg/mL, the average quantity of captured oocytes was 11.7 +/- 3.2 with a capture rate of 69.6%. Mean fertilization rates averaged 54% with a 20.7% pregnancy rates using the transference method. After analyzing the fertilization rate in each group, a statistically significant linear correlation was observed (P = 0.547, CI 95%) with the pregnancy rate. After assigning patients to two different groups: conventional IVF and ICSI, a higher positive correlation was observed (P = 0.827, CI 99%) in the first group. No significant differences were observed in the remaining parameters between both groups, excepting oocyte maturity, where greater prophase I and metaphase II percentages were observed in the ICSI group. When 50% fertilization was taken as the cutting point, a 78.19% negative predictive value was determined, with a 25% positive predictive value, 77.5% sensitivity, and 25.6% specificity. CONCLUSIONS: A fertilization percentage greater than 50% can be used as a pregnancy predicting factor in in vitro fertilization programs.

Adult↗
PubMed2006

[Relationships among human follicular fluid-induced acrosome reaction, sperm morphology and in vitro fertilization rates].

OBJECTIVE: To assess the relationships among human follicular fluid-induced acrosome reaction, sperm morphology and in vitro fertilization rates. METHODS: The relationships among human follicular fluid-induced acrosome reaction, sperm morphology and in vitro fertilization rates were investigated by Spearman rank correlation in 79 infertile couples. And the sperm morphology analysis was performed by crystal violet staining and based on strict criteria. RESULTS: A significant positive correlation was found between the percentage of human follicular fluid-induced acrosome reaction and that of normal sperm morphology (n = 49, r = 0.3763, P < 0.01), but no significant correlation was observed either between the percentage of human follicular fluid-induced acrosome reaction and in vitro fertilization rates or between that of normal sperm morphology and in vitro fertilization rates (n = 21, r = 0.2666, P > 0.05 and n = 50, r = 0.0018, P > 0.05, respectively). CONCLUSION: There is a significant positive correlation between the percentage of human follicular fluid-induced acrosome reaction and that of normal sperm morphology, but no such correlation either between the percentage of human follicular fluid-induced acrosome reaction and in vitro fertilization rates or between that of normal sperm morphology and in vitro fertilization rates.

Acrosome Reaction↗
PubMed1982

Fertilization rate and early embryonic loss in Brahman crossbred heifers.

The fertilization rate and incidence of embryonic loss in virgin Brahman crossbred heifers between d 3 and 35 postinsemination (d 0 = first day of estrus) were determined. One hundred fifty-five virgin heifers, maintained in a dry lot, received approximately 22 Mcal.head-1.d-1 and were allotted to one of three groups (d 3, 16 or 35) according to body weight at the time of estrous detection. Seven empty ruptured zona pellucidae (ERZP) were recovered from five heifers in the d 3 group. It was impossible to determine whether the ERZP originated from fertilized or unfertilized ova and whether they were ovulated at the estrus immediately preceding or during a previous cycle. Consequently, the fertilization rate (d 3) was calculated to be 80 or 93% depending upon whether the ERZP were included or deleted from the calculations, respectively. Because of the large number of ERZP recovered, a second study was conducted with an additional 21 virgin Brahman crossbred heifers from which ova were recovered on d 3 postinsemination. The results of the two studies were similar. The percentage of heifers with an embryo on d 16 was 78 (10% had degenerating embryos and 12% no embryos), and the percentage pregnant at d 35 was 72. The conclusions suggested from this study depend upon the classification of the ERZP. If the ERZP are designated as ova ovulated during a previous cycle or ova damage in the collection process and are deleted from the calculations, the fertilization rate is high (93%), and embryonic loss apparently occurs between d 3 and 35 (P less than .95). However, if the ERZP are classified as ova ovulated at the immediately preceding estrus, unavailable for further embryonic development, and are included in the calculations, the fertilization rate is comparatively low (80%). In the latter case, the primary loss of potential embryos occurs before d 3, and the loss after d 3 is negligible (P greater than .05).

Animals↗
PubMed1997

In vitro fertilization rate of mouse oocytes with spermatozoa from the F1 offspring of males irradiated with 1.0 Gy 137Cs gamma-rays.

Previous studies suggest that the spermatozoa from acutely irradiated male mice exhibit a reduced fertilization rate in vitro with the maximum decrease occurring for spermatozoa produced 6 weeks after irradiation (Y. Matsuda et al., Mutation Res. 142 (1985) 59-63). We have found that spermatozoa from unirradiated F1 males conceived 6 weeks after paternal F0 irradiation also exhibit a significantly reduced fertilization rate in vitro. After acute 137Cs gamma-irradiation yielding an absorbed dose of 1.0 Gy, adult CD1 F0 male mice were mated at weekly intervals with unirradiated female CD1 mice. Unirradiated adult males from F1 litters conceived 5 and 6 weeks after paternal F0 irradiation were allowed to mature. Their epididymal spermatozoa were evaluated for in vitro fertilization rates using oocytes from unirradiated 8-12-week-old CD1 females. The mean fertilization rate for spermatozoa from F1 males conceived 5 weeks after paternal F0 irradiation (80.74 +/- 15.74 SD %, n = 5) did not differ significantly from the control fertilization rate (89.40 +/- 10.94 SD %, n = 8). However, the fertilization rate for spermatozoa from F1 males conceived 6 weeks after paternal F0 irradiation (56.14 +/- 21.93 SD %, n = 5) was significantly less than the fertilization rate for control spermatozoa (p < 0.006) or for that of the F1 males conceived 5 weeks after paternal F0 irradiation (p < 0.04). These data suggest that spermatozoa obtained 6 weeks after paternal F0 irradiation can transmit a decrease in fertilization rate to the F1 generation males as well as exhibit decreased fertilization rate themselves when tested directly in vitro.

Animals↗
PubMed2001

Radical trachelectomy in early stage carcinoma of the cervix: outcome as judged by recurrence and fertility rates.

The recurrence and fertility rates in 30 women undergoing radical trachelectomy for early stage invasive cervical cancer at St Bartholomew's and Royal Marsden Hospital were reviewed. There were no recurrences, and the mean follow up was 23 months (range 1-64 months). Of 13 women trying to have a baby, eight had conceived with a total of 14 pregnancies and nine live births. Two were still trying and three were experiencing sub-fertility. There were seven premature deliveries and one late miscarriage. Six of the preterm births and the late miscarriage were associated with prelabour spontaneous rupture of membranes. This conservative yet locally radical procedure for a highly selected group of women who wished to preserve their fertility appears to offer a safe alternative to radical hysterectomy in early invasive cervical cancer.

Adenocarcinoma↗
PubMed1995

Does zona pellucida thickness influence the fertilization rate?

In human in-vitro fertilization (IVF), the cumulus oophorus is routinely removed to assess fertilization and hence the thickness of the zona pellucida is measurable. This study aimed to measure the thickness of the zona pellucida and to assess its influence on fertilization rate in IVF programmes. The zona pellucida thickness varies from 10 to 31 microns with a mean of 17.5 microns. One-way analysis of variance revealed that in IVF trials performed with normal semen, the zona pellucida of fertilized oocytes (16.6 +/- 3.2 microns) was significantly thinner than the zona pellucida of unfertilized oocytes (18.9 +/- 4.0 microns; P < 0.001). As measured on micro-injected oocytes, the zona pellucida thickness did not change between ovulation and 16-20 h after fertilization. Zona pellucida thickness was not related to ooplasm diameter. In conclusion, zona pellucida thickness appears to be an additional factor that should be taken into account when interpreting the fertilization rate. Zona pellucida thickness influences sperm penetration, even when the spermatozoa are considered normal. From a clinical point of view, a thick zona pellucida (> or = 22 microns) could be an indicator for the use of micro-injection procedures.

Adult↗
PubMed1989

Fertility rates in women in rural Turkey.

Fertility rates in married women, aged 15-44 years, in Yildizeli, were high. Only 86% of the pregnancies resulted in normal delivery, with 50% neonatal mortality, thus reducing the population increase in the area. Similar findings are seen all over rural areas of Turkey. The mean fertility rates in women, aged 40-44 years were similar to those of eastern regions of Turkey. The abortion ratios for 1979-1981 were also identical. Poor socioeconomic conditions and unsatisfactory public health services in the region are the probable cause.

Adolescent↗
PubMedDate not supplied

Age-specific incidence and prevalence rates of treated epilepsy in an unselected population of 2,052,922 and age-specific fertility rates of women with epilepsy.

BACKGROUND: There are no data on prevalence or incidence of treated epilepsy, and no data on fertility of women with epilepsy from an unselected UK population. METHODS: We used the General Practice Research Database to ascertain the incidence and prevalence of people with treated epilepsy in an unselected population of 2,052,922 people in England and Wales, and also age-specific fertility rates. We defined period prevalence of treated epilepsy as the number of people with epilepsy taking an antiepileptic drug per 100,000 people during 1995. The incidence of treated epilepsy was defined as the number of new cases of treated epilepsy per 100,000 people during the same period. We calculated fertility rates among women with treated epilepsy between 1991 and 1995 and compared these rates with the population rates for England and Wales in 1993. FINDINGS: The period prevalence of treated epilepsy in 1995 was 5.15 per 1000 people (95% CI 5.05-5.25). The prevalence was lower in children (age 5-9 years 3.16 [2.86-3.48]; 10-14 years 4.05 [3.70-4.42]), and higher in older people (65-69 years 6.01 [5.50-6.57]; 70-74 years 6.53 [5.97-7.14]; 75-79 years 7.39 [6.73-8.11]); 80-84 years 7.54 [6.78-8.39]; 85 years and older 7.73 [6.98-8.66]). The incidence of treated epilepsy was 80.8 per 100,000 people (76.9-84.7). The incidence was lower in children (5-9 years 63.2 [50.5-79.1]; 10-14 years 53.8 [42.4-68.3]) and higher in older people (65-69 years 85.9 [68.5-107.3]; 70-74 years 82.8 [65.0-105.2]; 75-79 years 114.5 [116.9-179.2]; 80-84 years 159 [125.2-202.6]; > or = 85 years 135.4 [100.4-178.7]). Fertility was lower among women with treated epilepsy, with an overall rate of 47.1 livebirths per 1000 women aged 15-44 per year (42.3-52.2), compared with a national rate of 62.6 in the same age-group. The standardised fertility ratios were significantly lower between the ages of 25 and 39 years in women with epilepsy (p<0.001). INTERPRETATION: Compared with previous studies, we found that the incidence of epilepsy was higher in elderly people and lower in children. The prevalence rates also increase with age. Women aged 25-39 years with treated epilepsy have significantly lower fertility rates than those in the general population. Research is needed to identify any potentially preventable causes for the low fertility rates.

Adolescent↗
PubMed2001

Effect of time of insemination on number of accessory sperm, fertilization rate, and embryo quality in nonlactating dairy cattle.

Two experiments were conducted to determine the effect of insemination time on number of accessory sperm per embryo (ovum), fertilization rate, and embryo quality. Semen was collected from three fertile Holstein bulls and cryopreserved in egg yolk-citrate-glycerol. In experiment 1, cows were continuously monitored for behavioral estrus by the HeatWatch estrous detection system and were artificially inseminated (AI) with one 0.5-ml straw (25 x 10(6) sperm) at the onset of estrus (AI 0 h), 12 h after onset (AI 12 h), or received natural service at 0 h (Nat 0 h) from one of three bulls. From 150 inseminations, 115 embryos and ova (AI 0 h: n = 39; AI 12 h: n = 39; Nat 0 h: n = 37) were recovered 6 or 7 d after insemination. Fertilization rates differed between treatments (AI 0 h: 67%; AI 12 h: 79%; Nat 0 h: 98%). Median accessory sperm per embryo (ovum) also differed (AI 0 h: 1; AI 12 h: 10; and Nat 0 h: 27) and paralleled the fertilization rate. Embryo quality was not affected by insemination time or natural service. In experiment 2, cows received AI at 0, 12, or 24 h (AI 24 h) after the onset of estrus as determined by HeatWatch. From 154 inseminations, 117 embryos and ova (AI 0 h: n = 39; AI 12 h: n = 39; AI 24 h: n = 39) were recovered 6 or 7 d after insemination. Fertilization rates did not differ in experiment 2 (AI 0 h: 66%; AI 12 h: 74%; AI 24 h: 82%); however, a trend toward a higher fertilization rate accompanied AI 24 h. Median accessory sperm values increased from AI 0 h (1) to AI 24 h (4). Embryo quality declined with AI at increasing intervals after onset of estrus, as percentages of excellent and good, fair and poor, and degenerate embryos were as follows: 77, 15, 8; 52, 38, 10; and 47, 19, 34 for the 0-, 12-, and 24-h inseminations, respectively. Results indicate AI 12 h after the onset of estrus provides a compromise between potential fertilization failure (AI 0 h) and embryo failure (AI 24 h), despite increased accessory sperm per embryo (ovum) after AI 24 h. Artificial insemination 12 h after onset of estrus should optimize fertility of dairy cattle through an acceptable fertilization rate, number of accessory sperm per embryo, and desirable embryo quality.

Animals↗
PubMed2001

Effects of supplementation with free radical scavengers on the survival and fertilization rates of mouse cryopreserved oocytes.

BACKGROUND: This study was conducted to investigate the effects of supplementation with free radical scavengers on the survival and fertilization rates of freeze-thawed mouse oocytes. METHODS: Superovulated oocytes with cumulus cells were cryopreserved by slow freezing in propanediol combined with a rapid thawing protocol. The cryopreservation medium was supplemented with the antioxidant enzymes superoxide dismutase (SOD) and catalase, and with the nitric oxide (NO) scavenger, haemoglobin (Hb). RESULTS: The addition of 50 IU/ml SOD showed significantly higher survival and fertilization capabilities compared with control (P < 0.01). Oocyte survival was greatly increased by concomitant addition of SOD with 10 IU/ml catalase (P < 0.01). On the other hand, the NO donor (sodium nitroprusside) inhibited survival and fertilization rates (P < 0.05). Significantly decreased survival and fertilization rates were also observed following the addition of high concentrations (10(-3) to 10(-6) nmol/l) of the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). In contrast, significantly better oocyte survival and fertilization rates were detected with low concentrations (10(-7) nmol/l) of L-NAME. Oocyte survival potential was significantly increased by addition of Hb (1 microg/ml, P < 0.05). Moreover, oocyte survival and fertilization rates were significantly promoted by the concomitant addition of SOD with Hb (P < 0.01). CONCLUSIONS: These results suggest that supplementation of free radical scavengers, particularly combinations of SOD with NO scavengers in freezing and thawing media, improved the post-thaw survival and fertilization rates of cryopreserved mouse oocytes.

Animals↗
PubMed2001

Relationships between sperm motility characteristics assessed by the computer-aided sperm analysis (CASA) and fertilization rates in vitro.

PURPOSE: Some studies have suggested that computer-aided sperm analysis (CASA) estimates of concentration and movement characteristics of progressively motile spermatozoa are related to fertilization rates in vitro. However, it has also been suggested that the greater number of motility parameters assessed by CASA does not imply more precision in predicting fertility. This study was carried out to investigate the relationships between the CASA estimates and fertilization rates in vitro. METHODS: Semen quality analysis was performed using CASA in 136 in vitro fertilization-embryo transfer (IVF-ET) cycles with at least 3 oocytes collected. The CASA estimates before and after swim-up were compared between 108 cycles with fertilization rate > 50% ("good" group) and 28 cycles with fertilization rate < or = 50% ("poor" group). RESULTS: Before swim-up, there were significant correlations between fertilization rates and CASA estimates, including amplitude of lateral head displacement (ALH) (r = .269), curvilinear velocity (VCL) (r = .297), straight line velocity (VSL) (r = .266), and rapid sprm movement (Rapid) (r = .243). There was also a significant correlation between the fertilization rates and straightness (STR) after swim-up (r = -0.178). As for sperm movement characteristics, there were significant differences of ALH (p < .005), VCL (p < .001), VSL (p < .005), and Rapid (p < .01) between "good" and "poor" groups before swim-up. After swim-up, there were significant differences of VCL (p < .005), average path velocity (VAP) (p < .005), and Rapid (p < .05) between the two groups. CONCLUSIONS: These results indicate that some of the CASA estimates provide reliable estimation of the fertilizing ability of human sperm. There were significant differences of the two sperm movement characteristics, including VCL and Rapid (before and after swim-up), indicating that the total distance traveled by rapid sperm movement might be important in human sperm fertilizing abilities.

Cell Size↗
PubMed1998

Sperm morphology evaluated by computer (IVOS) cannot predict the fertilization rate in vitro after intracytoplasmic sperm injection.

OBJECTIVE: To evaluate sperm morphology assessment using the IVOS (Hamilton-Thorne Research Version 3 Dimension Program, Beverly, MA) system in prediction of fertilization rate in vitro after intracytoplasmic sperm injection (ICSI). DESIGN: A prospective clinical study. SETTING: Diagnostic andrology laboratory and assisted conception service. PATIENT(S): Thirty-five patients from the ICSI program were evaluated. Semen samples were analyzed using a computerized system for conventional semen parameters, sperm movement characteristics, and sperm morphology. Only patients with three or more metaphase II (MII) oocytes available were studied. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Fertilization rates in vitro after ICSI were compared according to the sperm morphology obtained from the IVOS system. RESULT(S): Linear regression analysis of fertilization rates against the sperm parameters assessed by computer (IVOS), which included conventional semen parameters, sperm movement characteristics, percentage of normal sperm morphology, and percentage of each specific abnormal sperm morphology, did not reveal any significant correlations. The mean (+/- SEM) fertilization rates in the healthy prognosis group (normal sperm morphology > or = 4%) and poor prognosis group (normal sperm morphology < or = 4%) were 82.4 +/- 4.0% and 75.0 +/- 3.8%, respectively. There was no statistically significant difference in the mean fertilization rate between both groups. Moreover, no statistically significant difference was found in overall fertilization rates in vitro between the two prognosis categories (79.6% versus 78.0%). CONCLUSION(S): Sperm morphology obtained from the IVOS system is not related to the outcome of ICSI and cannot be used for prediction of fertilization rate in vitro after ICSI.

Adult↗
PubMedDate not supplied

Intermediate determinants of racial differences in 1980 U.S. nonmarital fertility rates.

There are four major determinants of racial differences in nonmarital fertility rates in the U.S.: differential sexual activity (exposure to risk); differential in spontaneous and induced abortion; differential contraceptive use (including method efficacy); and differential legitimation, through marriage, of births conceived out of wedlock. Racial differences in all four indicators encourage higher black than white nonmarital fertility rates in every age-group examined; however, the relative contribution of each determinant to differences in nonmarital fertility varies according to age. The gap between whites and blacks in contraceptive use is of greatest concern to policy-makers, because family planning effectiveness can, at least theoretically, be changed by program effort. However, even if black women and white women had equivalent levels of contraceptive use, sexual activity and recourse to abortion, there would still be substantial racial differences in nonmarital fertility rates because of the greater propensity among whites to legitimate premaritally conceived births.

Abortion, Induced↗