It A low hCG level could mean the embryo has a slower implantation process. Group Leaders communicate with staff moderators and escalate potential violations for review, but they dont moderate discussions. Briefly, in IVF and ICSI cycles, long luteal phase pituitary down-regulation with nafarelin or buserelin was followed by ovarian stimulation with either urinary or recombinant FSH. (i.e., 700%). Our study did not include comparison with spontaneous pregnancies, but others have reported that early HCG in spontaneous pregnancies is higher than that in the IVF pregnancies (Tulchinsky et al., 1996; Ertzeid et al., 2000). The most sensitive, accurate and reliable pregnancy test is a blood test for the presence of beta HCG , often just called "beta". Conclusions: Patients with ectopic pregnancies were also associated with low hCG values with the median concentration of 42.56 IU/l. Thus our results are equally applicable to double and single embryo transfers. Do you have a repeat draw scheduled? Re: HCG levels for a twin pregnancy? Does a failed blastocyst IVF cycle predict future cycle outcome? Beta HCG levels vary according to the gestational age. Early -hCG levels predict live birth after single embryo transfer. I think in the IVF world we have been burned so many times before that we worry no matter what. There are usually three beta hCG tests (assuming the first and second are positive). When two or more follicles reached a diameter of >17 mm (in TVS), 10 000 IU of HCG was administered. In our series, the median HCG concentrations in viable pregnancies were about 4-fold compared with those in non-viable ones, which is in agreement with the results reported before (Qasim et al., 1996; Bjercke et al., 1999). Might be a slow starter. If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. We think she was a late implanter so numbers really low at first but then got right on track and ultrasounds have been good! since the most important part is for HCG to double in 48-72 hours .Hopefully it does . It is used to diagnose pregnancy and a result greater than 5 mIU/mL is generally considered positive. In general, a beta hCG level of over 100 is generally considered a good, positive result. Statistical analysis was performed using NCSS 2000 software. P. Poikkeus, V. Hiilesmaa, A. Tiitinen, Serum HCG 12 days after embryo transfer in predicting pregnancy outcome, Human Reproduction, Volume 17, Issue 7, July 2002, Pages 19011905, https://doi.org/10.1093/humrep/17.7.1901. Some calculators are easier to understand than others are. Pregnancy blood tests can detect hCG hormone levels as low as 5 to 10 mIU/mL. The intra-assay variation was 2.7-5.1% and inter-assay variation 1.6-3.9% at the studied HCG levels. The data on this IVF hCG calculator is not intended to be a substitute for professional medical diagnosis or advice. (, Ertzeid, G., Tanbo, T., Dale, P.O., Storeng, R., Morkid, L. and byholm, T. (, Frattarelli, J., Leondires, M., Miller, B. and Segars, J. The measured HCG values were non-normally distributed. Lol. Even though the data of outcomes from low beta hCG levels looks scary, remember that there are many normal, healthy pregnancies that start out with a low beta hCG. Our time point for HCG sampling was the earliest suggested as being useful (Legro et al., 1995; Qasim et al., 1996; Bjercke et al., 1999). Gold RS, Azem F, Yovel I, Wagman I, Amit A, Lessing JB. Of the 876 single euploid FETs, 91% (n=802) had a serum hCG >2 mIU/ml. Group Owners uphold the core values of the brand by reporting content that violates the community guidelines. have significantly higher hCG levels compared to singletons. But a blood test can detect it earlier. I am so glad to see that individuals get low numbers and still have successful pregnancies, Day 5 4AA (transfer was at 1:45pm, betas were all drawn around 8am). This also implies that the `vanishing twin' syndrome (early cessation of development of one twin) is rare. It takes longer to start the implantation process and achieve a high enough hCG level to get a positive pregnancy test. My doctor said it was fine to start off low and that the doubling every two days is whats really important. Our aim was to assess the clinical value of a single early HCG assay in ART pregnancies taking into account the aetiology and treatment of infertility. I had my fresh transfer at the beginning of December. Keeping my fingers crossed for you x, thats really reassuring to hear, thank you! My HCG 13 days after my 5 day embryo transfer was over 1,300 and my 16 day post-transfer test showed over 3,500. Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked. In viable pregnancies, the HCG concentrations in ICSI treatment cycles were a little lower than in other treatment groups. Cells from the placenta grow deep into the lining of the uterus, establishing a rich blood supply. Caution must be used in making too much of hCG numbers. We use cookies to help provide and enhance our service and tailor content. For my case, I should have more 8000 after two days? I feel so heartbroken and empty. If the level was less than 300, the ongoing multiple pregnancy rate was 9% (5/57). Your email address will not be published. @bridges2798 - thanks so much for the encouragement! Conclusion: Serum hCG concentration on day 12 following embryo transfer may be a useful prognostic tool in counseling patients regarding pregnancy outcome. The positive predictive value for a viable pregnancy at this level was 87% and the negative predictive value was 74%. There are cases of multiple pregnancy that reach values close to 600 mIU/ml within 14 days after embryo . Craciunas L, Tsampras N, Coomarasamy A, Raine-Fenning N. Cochrane Database Syst Rev. The lowest HCG concentrations (median 88 IU/l, P = 0.001) were observed in the cases with both male factor infertility and ICSI treatment. 2575 centile range). Successful ovulation is the first step to getting pregnant; get support from a licensed healthcare provider. Such an anxious time. 3 embryos made it to blastocyst. Good luck tomorrow! One hundred eleven patients had positive serum quantitative hCG levels 14 days post-ET; 89/111, or 80.2%, had ongoing pregnancies. Data from a study of 523 pregnancies after IVF fertility treatment. Oh my gosh! Some recent studies have shown that the rise could be as slow as 53% in two days and the pregnancy could still turn out to be normal. Stay relaxed and think positive thoughts. Every woman is different and has her own hCG numbers after IVF. Congratulations! and transmitted securely. UsedToBeGoldie member. In simplest terms, the beta hCG test tells you how much hCG is in the blood. Results: The median hCG concentration was 161.00 IU/l for viable autologous singleton pregnancies. think twice before sharing personal details, foster a friendly and supportive environment, remove fake accounts, spam and misinformation, delete posts that violate our community guidelines, reviewed by our medical review board and team of experts. official website and that any information you provide is encrypted Hoping it continues! When serum -hCG levels 12 days after transfer were evaluated according to the transfer day, the values that were most reliable in predicting clinical pregnancy were 57 mIU/mL for day 3 transfer cycles (sensitivity 71.2%, specificity 64.7%, CI: 0.59-0.79) (Figure 3), and 87 mIU/mL for day 5 transfers (sensitivity 71.2% . If your home pregnancy test is positive, your healthcare provider may offer a blood test to check your hCG levels. It is important NOT to take these numbers literally. I appreciate the encouragement. Neither was there a difference between the medians of the 18 natural and the 54 substituted cycles (111 versus 123 IU/l; NS). Male factor infertility was associated with viable pregnancies (P = 0.004) and tubal factor with non-viable pregnancies (P = 0.003); the lowest HCG level (88 IU/l) was observed in subjects with both male factor infertility and ICSI treatment (P = 0.001). Your doctor will let you know if there are any other fertility treatments they recommend before trying again. MeSH Blood tests give the best results when taken 7-8 days after ovulation. Your bloods on Monday will hopefully give you the assurances you need, but I can imagine the wait until then is very daunting. In a pregnancy cycle, they should be greater than 10 to 12 ng/ml to have a better chance of a good pregnancy outcome. You've spent a long time waiting for good news. Open (white) symbols denote viable pregnancies and closed (black) symbols non-viable pregnancies. These statements have not been evaluated by the Food and Drug Administration. Because of that, the test is scheduled for two days later in order to see if hCG levels double, as expected. To update your cookie settings, please visit the. September 2011. How Effective is Letrozole for Ovulation Induction? The earliest you should check is 9-10 days after a Day 5 transfer and 12-14 days after a Day 3 transfer. So this is my third transfer and am over the moon I'm pregnant but so scared since the level is low - but I guess for day 8 - it's okay. As this article explains, its the rise in hCG over certain periods of time thats more indicative of pregnancy than the numbers themselves. Introduction Progesterone is an essential hormone involved in the process of implantation and pregnancy maintenance. All content and information on this website are for informational and educational purposes only. English. All biochemical pregnancies were found at HCG levels <100 IU/l. A live birth with unexpectedly low serum human chorionic gonadotropin level on day 11 after blastocyst embryo transfer: a case report. There is no single hCG level or cut-off that defines a normal pregnancy. What's more important than the absolute beta number is if the number increases substantially over time. Serum hCG values for viable and non-viable pregnancies were compared by Students t test. Learn more about. E-mail: aila.tiitinen@hus.fi, Bergh, T., Ericson, A., Hillensj, T., Nygren, K-G. and Wennerholm, U-B. Pregnancies were classified as viable (live fetus at > or =22 weeks gestation) or non-viable (biochemical pregnancy, miscarriage, ectopic pregnancy and molar pregnancy). (, Glatstein, I., Hornstein, M., Kahana, M., Jackson, K. and Friedman, A. The median HCG concentration was 126 IU/l in viable pregnancies and 31 IU/l in non-viable pregnancies (P < 0.0001) (Table I). If the level was between 300 and 600, the ongoing . Thank you so much for that!! Day 10: By the 10th to 12th day of development, the blastocyst is fully implanted. Days after implantation relative to hCG values are estimated and not part of the study.) You have to use exact numbers, so you cant use basic hCG strips that you buy in a drugstore or pharmacy. In other words, it miscarries before an ultrasound can detect it. hCG levels below 5 mIU/mL are considered negative for The aetiology of infertility played some role in our study. That is a nice jump in 2 days. If theres any concern about a high hCG level, your doctor will review the test results and discuss the next steps. Assisted reproduction treatment (ART) entails a risk of ectopic pregnancy and early pregnancy loss. A chemical pregnancy refers to a pregnancy that has been identified only through a beta hCG test but failed to progress. My beta was 115 at 10dp5dt and now I am 18 weeks pregnant with twins. I now keep saying slow and steady wins the race! Optimal time interval between hysteroscopic polypectomy and frozen-thawed blastocyst transfer: A retrospective study. What It's Like to Find Out You're Pregnant Through IVF. But what's more important than the absolute beta number that helps determine normal levels is the rate of increase over time (it should double every 48 hours). I heard hcg doubles every 48 hours, does this apply to whatever baseline we have? Find outstanding clinics from more than 400 fertility clinics in the USA. Today I am 8dp5dt and had my beta done. Copyright 2023 European Society of Human Reproduction and Embryology. Within the uppermost decile (median 263, range 221683 IU/l), normal singleton pregnancy and twin pregnancy showed similar probabilities of 50%. My home pregnancy tests have been stronger every day but the digital one only said 1-2 weeks. Read More. Serum hCG-beta levels of postovulatory day 12 and 14 with the sequential application of hCG-beta fold change significantly increased predictability of pregnancy outcome after IVF-ET cycle. Neither odds of implantation nor clinical pregnancy were influenced by maternal age, BMI or blastocyst expansion grade. Reply. For example, a woman starts her IVF pregnancy journey with 5 days FET. Clinics recommend a two-week wait after your embryo transfer because taking a pregnancy test too soon after the frozen egg transfer often produces false results. Thank you, my levels had indeed increased to 629 today so perfect doubling rate! thanks! hCG levels are different for day 3 vs. day 5 transfers. Although the early embryo cleavage is delayed in ICSI-derived embryos and the fragmentation of embryos is increased, the implantation potential is comparable with IVF-derived embryos (Hsu et al., 1999; Frattarelli et al., 2000). Normally, you do your first pregnancy HCG blood test 14 days after embryo transfer. With that said, levels in the lower end of this range might indicate a problem with embryo implantation. Curious what individuals HCG levels were for a 5 day embryo transfer? Sign up for insider access, exclusive deals, and OBGYN insights! According to NYU Langone Fertility, the following occurs each day after IVF embryo transfer: Day 1: The blastocyst begins to hatch out of its shell. Enter the date of your first hCG test. After an embryo transfer procedure, it takes around 10-14 days to see the IVF results. It's produced by your placenta after conception. I had my transfer November 22nd with one frozen embryo. Patients who had serum hCG concentrations higher than 5IU/l on D12 post embryo transfer were stratified and evaluated. In many early IVF pregnancies, the hCG level will double every 48 to 72 hours. At day 12 after embryo transfer, each patient had her HCG level assessed. and if I may ask- do you expect a Girl? J Assist . Although the EP in our series were clearly associated with low HCG values, they could not be distinguished from the much larger group of other pregnancies with similar levels of HCG. But it also comes with emotional ups and downs. My transfer was at 12:30 and I am 8DPT based today baby 1: FET 9dp5dt - 153baby 2: 13dpo - 39. If the level was less than 300, the ongoing multiple pregnancy rate was 9% (5/57). For example, equal proportions of biochemical pregnancies, miscarriages, and viable pregnancies were observed at an HCG level of 3040 IU/l, which suggests that a second HCG reading a few days later would be helpful. Unable to load your collection due to an error, Unable to load your delegates due to an error. PLoS One. J Reprod Med. I had ectopic on Feb 2014 . To conduct an analysis that determines the level of hCG in the blood, it is advisable not earlier than two weeks after embryo transfer. I took tests all Hi folks,I have read the forum a lot over the last two years but written only once. Conclusions: A single HCG reading on day 12 after embryo transfer helps to plan the subsequent follow-up. Male factor infertility was associated with viable pregnancy, probably reflecting normal female fertility combined with suboptimal male fertility. So, if you were tested for hCG on March 10, 2017, you would choose or enter 10/03/2017. 2/8 would be 1dp, correct. Markers have been sought to distinguish between viable and non-viable pregnancies before verification of live intrauterine pregnancy by transvaginal sonography (TVS) is possible. Long post ahead. Eggs and sperm will be fertilized in vitro to create embryos. Group Owners uphold the core values of the brand by reporting content that violates the community guidelines. An hCG level of less than 5 mIU/mL is considered negative for pregnancy, and anything above 25 mIU/mL is considered positive for pregnancy. Use of this site is subject to our terms of use and privacy policy. thank you! Data on the outcomes were retrospectively retrieved from the records. An hCG level of 13,000-290, 0000 mIU/ml is reached by the end of the 1st trimester (12 weeks) whereupon it slowly declines to approximately 26,000- 300,000 mIU/ml by full term. hCG levels chart in weeks from DPO (days past ovulation): Step 1: Choose IVF treatment and input embryo transfer date, Step 2: Enter the first hCG test date andbeta hCG level, Step 3. If pregnancy still +, the woman returned at 5.5 weeks to confirm pregnancy was intra-uterine . Human chorionic gonadotropin was examined to evaluate pregnancy on days 12-14 after embryo transfer. (, Hsu, M-I., Mayer, J., Aronshon, M., Lanzendorf, S., Muasher, S., Kolm, P. and Oehringer, S. (, Hsu, M-I., Kolm, P., Leete, J., Dong, K., Muasher, S. and Oehninger, S. (, Legro, R., Paulson, R., Lobo, R. and Sauer, M. (, Ong, C., Liao, A., Spencer, K., Munim, S. and Nicolaides, K. (, Schmidt, L., Asch, R., Frederick, J., Rojas, F., Stone, S. and Balmaceda, J. doi: 10.1002/14651858.CD011537.pub2. The educational health content on What To Expect is reviewed by our medical review board and team of experts to be up-to-date and in line with the latest evidence-based medical information and accepted health guidelines, including the medically reviewed What to Expect books by Heidi Murkoff. @Praying4Baby86, oops, edited. At-home urine tests require higher levels of hCG to detect a pregnancy, typically at least 20 mIU/mL. I know it differs so much by pregnancy. Is this too low?? xx, Hi AmyK227 I don't have any direct experience on this, but everything I've read says that what counts is that HCG levels double every 48 hours or so. Congratulations! It does not constitute medical advice and does not establish any kind of doctor-client relationship by your use of this website. Will keep you posted! Twin gestations will have higher levels than a singleton gestation at the same gestational age. It has been suggested that HCG has more predictive value than other biochemical markers for assessing pregnancy outcome (Homan et al., 2000). Use our. The beta hCG will vary based on the type of embryo you transferred (was it fresh? Double measurements of serum HCG concentration and its ratio may predict IVF outcome. Beta human chorionic gonadotropin (b-hCG), the hormone that indicates that the fertilized egg has implanted into the uterine wall, rises at around 7 8 days after implantation. Create an account or log in to participate. Of the frozen embryo transfer cycles, 96 (70%) were substituted and 41 (30%) were natural. A Group Owner is a member that has initiated the creation of a group to connect with other members to share their journey through the same pregnancy & baby stages. It tells you if the rate of doubling is normal or not, and it may also indicate the likelihood of twins. You have done everything you can up to this point. In only two studies (Gold et al., 2000; Homan et al., 2000) have different treatments or causes of infertility been compared in relation to early HCG concentration and pregnancy outcome. eCollection 2020 Jun. Please select a reason for escalating this post to the WTE moderators: Connect with our community members by starting a discussion. There are no suggestions because the search field is empty. The higher the percentage of rise in hCG drawn two days following the initial beta, the better the chances for success. Good luck! To use an IVF hCG calculator for post-IVF treatment, you need to know: On the date of transfer, what stage will the embryos be in? Initially, hCG levels are quite high. Your lines from 10dp look great and looks like indeed , she was a later implanter ))) and with girls, HCG seems to start producing later than with boys. Find advice, support and good company (and some stuff just for fun). The mean -hCG concentrations based on maternal age (23-33 years vs 34-45 years) were obtained (357.9 + 276.7 vs 269.5 244.4 mIU/mL), where the differences in both groups did not differ significantly statistically (p = 0.206). Zboilov B, Bezinov J, Tkadlec E, Prochzka M, Oborn I, Sobek A Jr, Sobek A. HCG level after embryo transfer as a prognostic indicator of pregnancy finished with delivery. However, if your hCG level is falling, it is likely that the implantation was not successful. IVF Process Basics Success Rates IVF Costs IVF Safety and Risks Step 1: Before Treatment Step 2: Treatment Cycle Begins Step 3: Ovarian Stimulation Step 4: Oocyte Maturation Step 5: Egg Retrieval Step 6: Fertilization Step 7: Embryo Transfer Step 7: Embryo Transfer Step 9: Pregnancy Test Human embryos can produce hCG as early as 8 days after fertilization. Congratulations! In viable pregnancies, an exponential transformation gave a good fit to normal distribution allowing use of Student's t-test and one-way analysis of variance (ANOVA). my HCG numbers today were 16. Try and relax enjoy being pregnant! Bleeding During IVF - What's Normal and What Isn't? You need information from both of your hCG blood tests. This educational content is not medical or diagnostic advice. Next appt is in two weeks for an US. We therefore continue to include the assay of HCG 12 days after embryo transfer in our IVF protocol. Finally, you enter the results from the second test. Keep us posted! lower end of this range might indicate a problem with embryo implantation. The objective of our study was to use day 12 post-embryo transfer HCG concentrations to predict outcome of pregnancies following ART, taking into account the aetiology and treatment of infertility. If you are a human, do not fill in this field. hCG level rises rapidly during the first trimester and then declines slightly. Although I am a physician by profession, I am not YOUR physician. Im 16weeks 1day today and everything looks great! The last transfers of three embryos were carried out in 1994. The risk of adverse pregnancy (AP) outcomes such as ectopic pregnancy (EP), biochemical pregnancy (BP) and spontaneous abortion (SA) is greater in women undergoing ART compared with natural pregnancy. 2014 May-Jun;59(5-6):285-92. It is usually scheduled 1 month after the embryo transfer or 15 days after a positive hCG result. I'm going in for a second beta on Wednesday but was wondering if anyone else had their first betas tested this early and what the HCG level was. wow, such a hope promising post! Was just wondering if anyone else had such an early beta done? HCG level 15 days after embryo transfer AmyK227 3 months ago 8 Replies Yesterday at 15dp5dt I went for a blood test and my HCG is only 150. congrats on a BFP. What to Expect supports Group Black and its mission to increase greater diversity in media voices and media ownership. do you remember how your tests looked like on 9-10dp5dt? According to available research, it occurs in 7 to 42 percent of IVF cycles. That's a great number for only 8dpt but what will really matter is if it doubles! Materials and Methods: All women underwent GnRH agonist suppression and controlled ovarian stimulation with gonadotropin administration. Please whitelist our site to get all the best deals and offers from our partners. CONCLUSIONS: A single HCG reading on day 12 after embryo transfer helps to plan the subsequent follow-up. Here is what they found: The median hCG concentration was 126 mIU/mL in viable pregnancies and 31 mIU/mL in non-viable pregnancies (four times higher; P < 0.0001). Please enable it to take advantage of the complete set of features! So, what is a good first hCG level after embryo transfer? Doctor likes to see 80 at this point but it does mean a positive test. glad to hear its jumped Amy, I had low HCG and all turned out fine. Please specify a reason for deleting this reply from the community. In IVF cases, it can be caused because you have used an hCG drug-like Ovitrelle or any other drug to trigger the ovulation, and the hCG lasts . The level of hCG may double every 2-3 days in early pregnancy. The women underwent previously described treatment protocols (Simberg et al., 1998; Tiitinen et al., 2001). Up from 34 two days ago. One study found that median hCG levels on Day 13 after a fresh embryo transfer were 329 for women with one baby and 544 for women carrying twins. 2005-2023Everyday Health, Inc., a Ziff Davis company. There is no way to predict who will and wont be able to achieve a healthy pregnancy. In 1999, the number of embryos transferred per cycle was 1.7. The night after embryo transfer, all patients started vaginal progesterone. It is really the doubling time that matters. 2022 Oct;39(10):2355-2364. doi: 10.1007/s10815-022-02606-w. Epub 2022 Sep 8. It's the outer layer of this sac that develops into the placenta. What Does a Round or Cycle of IVF Even Mean? Records of the subjects who conceived following ART during that period were analysed. 2000 Jun;15(6):1221-4. doi: 10.1093/humrep/15.6.1221. Sometimes, women will ask if their hCG level in doubling timeis normal. Here's what happens after an embryo transfer day by day: Day 1 and 2: The blastocyst hatches out of its shell and begins to try to attach itself to the uterus. The HCG is produced by the embryo, and is the embryo's signal to the mother that pregnancy has occurred. Several studies have confirmed that serum -hCG is a reliable index for predicting early pregnancies at 12-18 days post-transplantation (dpt). Most home tests can detect pregnancy 4 to 5 days before the next expected period. Below are the average hCG levels during the first trimester: 3 weeks LMP: 5 - 50 mIU/ml 4 weeks LMP: 5 - 426 mIU/ml 5 weeks LMP: 18 - 7,340 mIU/ml doi: 10.1371/journal.pone.0240882. Serum hCG values for viable and non-viable pregnancies were compared by Student's t test. Get your query answered 24*7 only on | Practo Consult . Serum human chorionic gonadotropin level measured 17 days after oocyte retrieval can predict final clinical pregnancy outcomes in IVF/ICSI treatment cycles. We observed similar HCG concentrations in singleton pregnancies regardless of the number of embryos transferred. 3 While you should report any unusual bleeding to your doctor, spotting alone is not necessarily a good or bad sign. Lower levels can indicate a failed pregnancy or an ectopic pregnancy. Shipping is not available outside of the United States. Create an account or log in to participate. Male factor infertility and ICSI are associated with relatively low HCG values in viable pregnancies. Enter the second hCG test date and beta hCG level, Step 4: Calculate and examine the results, Example Results from an IVF hCG Calculator, IVF Comparison Tool: Compare Fertility Clinics Success Rates, Fertility Clinic Rankings in the United States, IVF Cost Calculator: Costs of Own eggs, Donor, Surrogate, FET, ICSI and PGD, IVF due date calculator with one baby,twins or triplets, including 3 day and 5 day, IVF Success Rate Calculator Predict the Likelihood of Live Birth After IVF, Own eggs, Fresh donor eggs, Fresh donor embryos, consider the egg retrieval date as 0 day of DPO date, 14 days later after the egg retrieval date, consider embryo transfer date as 3 days of DPO date, 11 days later after the embryo transfer date, consider embryo transfer date as 5 days of DPO date, 9 days later after the embryo transfer date, Tell you the difference in levels from the first and second test, as a percentage (i.e., +525/+700% or -25/-67%), Give you a 2-day increase rate, regardless of how many days passed between your tests. Probabilities of each type of outcome related to the HCG level are given. In some IVF cycles, fresh embryos are transferred, while in other cases, frozen embryos can also be transferred to the uterus. What is a Good First hCG Level after Embryo Transfer? I'm trying not to stress, but of course easier said than done. One study of 523 IVF pregnancies found that betas over 200 IU/L at this time had the greatest chance of success. Also, the day you have your embryo transferred matters, too. An abdominal ectopic pregnancy following a frozen-thawed ART cycle: a case report and review of the literature.